Looks like it wasn’t a fluke after all… He’s rolled over at least a couple times a day now, every day since we first noticed him doing it. He’s only rolling over in the one direction (to the right from belly to back) so far, but hey, he’s got it! :)
He’s getting better with his sitting, too, from day to day, and he’s starting to really get his knees up under himself for crawling, too. Whee!