I understand that hindsight is 20/20 and it is easy from the modern day to point out examples like Bleeding Kansas, John Brown's Raid, and a string of ineffectual Presidents as setting the stage for the Civil War, but did citizens pause and consider the gravity of their actions or was the Civil War more of a surprise?
The civil war was definitely not a surprise. I wrote this answer recently to a similar question, which goes into more detail than I will here. Not only were predictions of war being made regularly throughout the 1859-60 presidential campaign, but many members of one of the four political parties in that year's election (the Southern Democrats) were essentially promising a civil war should Lincoln be elected and their attempt at secession be resisted.
That answer mostly focuses on the period of 1859-61, but going back further, these predictions were rather routine at earlier flashpoints, too. Countless editorials during the Bleeding Kansas crisis characterized the turmoil as the beginnings of a civil war that wouldn't be resolved until the slavery issue was resolved one way or the other once and for all.
During the Crisis of 1850 that ended with the Compromise of 1850, similar predictions and accusations were made. For example, some pro-slavery petitioners petitioned Congress for a dissolution to the Union if no favorable compromise could be reached, and Sen. Lewis Cass of Michigan (who was also the most recent Democratic Party candidate for the presidency) characterized attempts at disunion as "seeking civil war, for that is the meaning of dissolution".
Even earlier, South Carolina's Nullification Ordinance during the Nullification Crisis of 1832-33 actually put it into law that they would attempt to secede through military (militia) force if their demands weren't met - civil war as a matter of actual legal policy. And then back during the Missouri Compromise debates in 1819-20, there were similar fears of civil war. Former presidents Adams and Jefferson exchanged letters fearing the end of the nation if a compromise weren't reached.
By 1860, there surely were some who thought "we've heard this all before" and thought it was more "boy who cried wolf" rhetoric that wouldn't actually come to pass. But more often than not, commentators were realistic about the threat. If Lincoln were elected, there was little doubt some Southern states were going to try to secede, take federal property with them, and would attempt to do so by force of arms if need be. The only question was how to respond to their violent and illegal acts. So when Lincoln was elected and that is what happened, nobody was particularly surprised that war resulted.
For more details and citations, see my previous answer.