Thanks for the helpful information guys! Unfortunately, things did NOT work out...he was a bit of a spitfire. I was just going to walk and trot on him today, but he wanted to go faster--so when I tried to slow him from cantering, he didn't want to listen so he started bucking a bit. I did fall off, but it was a short fall since I held on until he stopped abruptly, and I was wearing a helmet. His owners did tell me when I met him the first time that he'd never bucked/reared/kicked/etc., and I know the people well so I definitely believe them; but that just shows how seriously important it is to try a horse before buying. I understand that horses have bad days sometimes like we people do, but as a person who's searching for my first horse, I sorta want the first experience with the horse to be great.
I guess I'll keep looking. The perfect horse will roll around eventually.