She mentioned that they sent out their best ships, the aircraft carriers out on patrol, rather than the normal patrol ships. Why else would they have sent out the aircraft carriers?
Just to build on those answers, by the Fall of 1941 everyone was pretty clear that war was a very real possibility and was planning accordingly.
For several years defense bills had greatly expanded funding for the War and Navy Departments, new ships, aircraft, and vehicles were being designed and funded, with peacetime drafts starting in 1940.
But the idea that Pearl Harbor itself was going to be where the war broke out was pretty far down the list of concerns. And what threats were actively considered where of a different nature. Notably the worry was a quick raid by a sub or light surface forces, perhaps trying to lure the ships in port out into an ambush where they would be sunk or attacked in deep water. Or possibly a rogue skipper on a suicide mission in the vein of Japan's engagements on the Asian mainland in the 30's. Along with the more commonly covered worries about sabotage by enemy agents. That said leaders from Kimmel and Short on down made clear that they did not feel they had sufficient scouting and patrol assets to even guard effectively against those possibilities.
And really until late 1940 those options were the only ones actively considered by the Imperial Japanese Navy, as the scheme to get a group of carriers and escorts of Oahu, with fuel to fight, and aircraft that could really do damage required near herculean efforts and a laundry list of new skills and equipment to be developed in a very short time.
And in the end anyone and everyone knew that if Japan struck at the US and European powers the initial focus would be South, the Dutch East Indies, Malaya, and very likely the Philippines to secure access to and sources of the valuable resources like oil, rubber, and rare earth metals to fuel the war economy. Without seizing them the whole undertaking was pointless and doomed no matter how the US Pacific Fleet acted in the early days of the war.
That said aircraft carriers, the IJN's included, don't just sit in port all day. In order to do their jobs they need to be underway at sea, even if it is just to get their air group experience so they dont get rusty. While the IJN had also used their carriers to support the war in China and as aircraft transports to their island holdings. By way of comparison both carriers in service by the US Pacific fleet were out on transport runs on December 7th(Enterprise was almost back from a run to Wake, Lexington was on her way to Midway), while a 3rd Saratoga had just docked in San Diego to meet her sir group after a refit in Washington State. While a peacetime navy will have ships spending plenty of time in port, in part honestly to save money if worried, that doesnt mean they dont routinely weigh anchor and get underway. And in 1941 once out of sight of land the only way to get an idea of their location and mission is to either get a sighting report from something of yours like a ship or plane, decrypt their radio signals, and maybe if you know their callsign as it were you could triangulate their position if they were broadcasting and you had the right SIGINT equipment.
That said the Kido Butai also left for Pearl under radio silence, so at first it was simply that they had dropped off the board or were intentionally being quite. But against the background of tensions, goals clear to all in the SW Pacific, and the huge distances and hurdles to actually attack Pearl all obscure that Hawaii might be at more than a fleeting risk in the general mobilization and fleet movements just before the outbreak of war.
There were certainly some in the US that showed more concern than others, but hindsight makes grasping half at straws and having a vague sense of worry look much more like great foresight than it was. While additional signs that the threat from the IJN was far more real than might have been considered by many, and their penchant for bold opening strikes(such as in the tradition of the attacks on the Russian Fleet at Port Arthur in 1905) greater appreciated if it were not for a strong veneer of simple racism coloring much analysis of the situation. That is a dimension that simply can't be ignored and permeated how many saw and thought of the Japanese threat and planned accordingly.
You may be interested in 'At Dawn We Slept' by Gordon Prange. While parts have not aged well it is still one of the major works on Pearl and its planning/movements leading to it. 'Countdown to Pearl Harbor' by Steve Twomey is another newer book too that I quite enjoy.
While there’s always more to say on the subject, you might be interested in these previous answers by u/DBHT14: