Could be either. Read somewhere recently that the physical tastes really do change a lot for LOs - not sure where though! So if they say they no longer like it, it could be a totally different taste for them.
I personally would keep offering a variety of food, making sure there's stuff in there that he does like. Let him decide whether or not he eats it. I really believe that our job is to serve it and theirs is to decide what to do with it. I think making a big deal of it/rewarding/forcing just creates issues around food.
LJ has always eaten what she wants, when she's hungry. Never praised her once and we have varied sating patterns. Xxx