Keep an eye on his eating, his activity level, and going to the bathroom. Could be a mood - could be he's not feeling well?
I hate potentially alarming someone when there may be no problem, but changes in behavior are sometimes indications that kitty is sick, and it can be hard to tell when it's just kitty being kitty or when there's maybe a problem. We were overly cautious parents at first and were frequently running one of the cats to the vet, so over time we learned. But just remember that changes in behavior are one of the very few ways kitties have to tell us there's a problem.
For our kitty, it was kind of similar. He seemed to eat, play, and go to the bathroom like normal - but when we came into a room, he'd turn his back to us. He started showing less interest in play and food, and then when we entered a room, he'd leave. Had we been as overly cautious as we originally were, we'd have gotten him to the vet sooner. As it was, it was close by the time we noticed he had actually become pretty listless (we did have five other cats dividing our attention). He was very, very anemic. Turned out he has an autoimmune disease that needed to be treated - and then.
So if he goes back to his "normal ways," I wouldn't worry. Or maybe this is a new routine? Like I suggested before, just keep your eye on his eating, his activity, and his bathroom habits.