Absolutely, and quite a few. Let's look at the whole picture of that time and look at some major efforts towards eliminating slavery, then we can examine the very specific situation of Jefferson.

As you establish in your question slavery was around long before the Founding Fathers showed up. Benjamin Franklin is probably the oldest person anyone that's not a colonial history nerd would call a Founding Father - he was older than both of Jefferson's parents, older than both of Hamilton's parents, older than Adams' mom, and was even older than Washington's mom, yet when he was born (1706) common and codified hereditary and racial enslavement of Africans in British America had effectively existed for over 40 years already and did so in numerous colonies (1662 Va, 1661 Barbados, etc). In Massachusetts they began codified enslavement and removal of Natives much earlier than that, and in 1639 gentleman traveler John Josselyn met enslaved Africans in New England and wrote about it. Slavery was not at all new in the American colonies by the time the Founders were born, it was already deeply engrained as a proper and natural necessary structure within civilized society.

The first internal group in this Anglo society to speak out against enslavement specifically in British America was the Friends, or those known as Quakers to the outside world. A congregation (actually just four men) signed the first petition in North America against enslavement, but it was only aimed towards other Friends and nothing really came of it anyway. That was 1688 in Germantown, Pennsylvania. But it does signify the resolve of some Quakers and later on Friends like Benjamin Lay (b.1682) were able to speak against the practice starting in the early 1700s. He didn't hold any humans in bondage, in fact he watched a man commit suicide to escape a life in bondage and that really had an impact on his beliefs (he was also a vegetarian). He moved to Penn's religious paradise only to find slavery there, too (Wm Penn personally held humans in bondage but ultimately did free some, as an early example). Lay would attend meetings and when a slave holder would rise to speak he would say things like, "There's another Negro master!" Another example, once he stood outside a meeting as it snowed having one foot and lower leg without any covering at all as folks repeatedly asked that he come inside, then he finally replied, "Ah, you pretend compassion for me but you do not feel for the poor slaves in your fields, who go all winter half clad." He also attended a meeting in which he stabbed a Bible that had a dye pack, then began flinging the red dye spilling out on attendees as he spoke of the evil that was slavery and warning of the wrath of God against those participating, saying, "Thus shall God shed the blood of those persons who enslave their fellow-creatures." Eventually he was kicked out of the Society of Friends entirely after writing a harsh criticism of fellow Friends because they held humans in bondage (and his little-f friend Benjamin Franklin is the printer that would publish it for him). That's the first real abolitionist in America, and he was pretty awesome. He was also about 4'7" tall with a slight hunch and an unusually large head, so he was one hell of a character, and he helped to influence the entire Friends Society. John Woolman came next and published works advocating for the poor and in support of abolition, though never with the same theatrics as Lay had performed.

Around this time a true gentry class in America was really developing. Lay moved to Barbados (from England) in 1718, the same year Lt Gov Spotswood sent Lt Maynard to NC to kill the pirate Blackbeard and two years after he led an expedition that reached the Shenandoah Valley. A decade before that one of the first books on dancing had been translated into English and Spotswood, being the first person to inhabit the Governor's Palace in Williamsburg, VA, capital of the colony, loved to host dances and balls. This is also when many American folks, like John Wayles and Augustus Jay, started profiting from funding the shipment of humans in bondage to America, and this built empires of wealth that provided an opportunity for this class to fully develop which continued for the next 50 years. In Pennsylvania construction began on what we call Independence Hall. Maryland tobacco plantations swallowed the landscape and Lord Baltimore had a town founded in his name. Virginia developed a high society as they pushed right up against the Blue Ridge Mountains to the west. North Carolina became more than a refuge for those that didn't coexist well with Chesapeake society, South Carolina plantations grew absolutely massive and both Carolinas become Royal Colonies. Georgia was formed to shield S.C. from the chaos beyond the Spanish recognized border with the English, then that was changed in the War of Jenkins' Ear to greatly favor the british and grant them the current coastal region of Georgia. In the meantime those gentry class men became prominent in society and all kinds of growth, including from enslavement, built their communities around them. Then came our founders, born into this really messy situation in which slavery had already been utilized to extremes. Many of them began inheriting humans in bondage, and some doing so at early ages (like Washington at age 11). This all defined how the majority of our founders would be raised and what societal influences they would be facing as they developed into educated gentry gentlemen befitting of society's expectations.

While they grew up and Lay performed... Anthony Benezet was a French Huguenot born in 1713. His family had their property seized when he was about two and as a result they fled France, eventually winding up in Philadelphia (1731). Shortly after arriving Benezet joined the Society of Friends, married a preacher, became a teacher, started tutoring blacks (free or enslaved), started an all girls school, and finally he wrote an epistle to his Friends on his belief that Friends and enslavement were simply incompatible. Just before we declared our independence he started the first abolition society in the British world (1775), the Society for the Relief of Free Negroes Unlawfully Held in Bondage. The Quaker community had kept pace as well and by 1774 you could hold humans in bondage or be a Friend, but not both. Along this path many Friends had, by one means or another, released their "property" to be rightfully free. Some Friends paid those other Friends who held humans for the humans' freedom, some charged those they held in order to purchase their own freedom, and others just emancipation them outright. Some even compensated, to a degree, those they had themselves just freed. So here we find an answer direct to your question in that numerous Quakers removed themselves from enslavement after being complicit in the practice. Penn is a great example. The king owed Penn's late father 16,000£, so he gave him what became Pennsylvania to settle the debt in 1681. In 1682 Penn founded both the colony of Pennsylvania and the city of Philadelphia, and at that time it was probably the most free and equal location in all of British society. Still, slavery was not prohibited. Penn "owned" 12 humans before departing America for the last time, and he had conflicting wills about their emancipation, his earliest declaring them free but that being omitted from later versions. While he did not hold them all some served his estate even after his death. Eventually and under the influence of the Friends, and before Lay ever left England for Barbados, Pennsylvania passed legislation to greatly tax importation of enslaved souls, then passed legislation to prohibit their importation entirely. And they passed it again. And again (1711, 1712, 1714, 1717). Every single one was overturned back in England and in the name of commerce. This is the first real example in British America of an attempt to began a path to ending the practice by an American (colonial) legislative body, and England said, "No, you can't do that."

Ben Franklin held humans in bondage starting in the late 1730s. He became convinced the practice was wrong in the 1750s and began to seperate from the practice, yet he did not stop holding humans in bondage himself until 1781. He was named president of Benezet's society after Benezet, who had married the cousin of Franklin's wife, died in 1784, and in 1787 Franklin was asked to represent the Society at the US Constitutional Convention. His last act in public life was petitioning Congress to address the injustice of enslavement on behalf of the Society, in 1790. And a little over a decade after Franklin's death Benjamin Rush became president of the Society. He (along with Thomas Paine, who was himself the son of a Quaker) joined the Philadelphia Society years earlier and had been very outspoken about ending slavery. Despite this he had purchased William Grubber and held him until 1794, only nine years before becoming president of the first abolition society.

Cont'd

I am not sure if a count has been made, but there were at least two examples of other southern political leaders who expressed equal dismay over it around the same time. There's William Pinckney, of Maryland, who made a speech in the House of Delegates in Annapolis in Nov. 1789:

Iniquitous and most dishonorable to Maryland, is that dreary system of partial bondage, which her laws have hitherto supported with a solicitude worthy of a better object, and her citizens by their practice countenanced.

Founded in a disgraceful traffic, to which the parent country lent her fostering aid, from motives of interest, but which even she would have disdained to encourage, had England been the destined mart of such inhuman merchandise, its continuance is as shameful as its origin.

Pinkney, W. (2010). Speech of William Pinkney, Esq. in the House of Delegates of Maryland, at their session in November, 1789. Gale ECCO, Print Editions.

There's also a letter by Patrick "Give Me Liberty or Give Me Death" Henry in 1773 :

It is not a little surprising that Christianity, whose chief excellency consists in softening the human heart, in cherishing and improving its finer feelings, should encourage a practice so totally repugnant to the first impressions of right and wrong; what adds to the wonder is, that this abominable practice has been introduced in the most enlightened ages, times that seem to have pretensions to boast of high improvements in arts, sciences and refined morality, have brought into general use and guarded by many laws, a species of violence and tyranny, which our more rude and barbarous, but more honest ancestors, detested. Is it not amazing, that at a time when the rights of humanity are defined and understood with precision, in a country above all others fond of liberty, that in such an age and such a country we find men professing a religion the most humane, mild, meek, gentle and generous, adopting a principle as repugnant to humanity, as it is inconsistent with the Bible and destructive to liberty?

But then, the important bit:

Would any one believe that I am master of slaves of my own purchase? I am drawn along by the general inconvenience of living without them. I will not, I cannot justify it. However culpable my conduct, I will so far pay my devoir to virtue as to own the excellence and rectitude of her precepts, and to lament my want of conformity to them.

I believe a time will come, when an opportunity will be offered to abolish this lamentable evil; every thing we can do is to improve it if it happens in our day, if not, let us transmit to our descendants together with our slave a pity for their unhappy lot and an abhorrence for slavery. If we cannot reduce this wished for reformation to practice let us treat the unhappy victims with lenity.

It's impossible to believe that Henry and Pinckney were unusual, really. The evils of slavery were obvious. But somewhat like St. Augustine's famous " save me, lord; but not yet", intelligent slave owners could lament that slavery existed ( it predated Henry's letter by more than a hundred and fifty years) but plead that slaves were a necessity: they were " drawn along by the general inconvenience of living without them". Like Jefferson, it gave them a genteel life, and like Jefferson they could express hope that it would be ended , well, soon...by someone else, somehow. Until then, pass the wine, and try not to flog the un-hired help.

What Henry and Pinckney could not foresee was that the immense profits that from slave labor in the cotton industry of the 19th c. would make that even harder to do. The greatest chance to abolish slavery was actually in their time, not in the future. In the 1840's, there'd be less talk of eradicating slavery in the south, more lofty statements about somehow doing it kindly.