Marnie, he sounds very much like a three year old to me
I kept hearing all about the "terrible twos" and thinking with my first child, wow, we lucked out, he's been so happy and carefree all through the twos - and then three hit and wow! Not so much fun
I would go ahead and ask his preschool teachers what they've noticed at school, but I wouldn't overly worry about anything unless they bring something up that's a concern. Chances are this is just a phase (although it might be a long phase!).
Re asking him questions and getting the "I don't know" reply etc - I'd just let go when that happens for awhile, and instead talk to him when he's open to talking. My kids have never liked me asking "what did you do in school today" type questions. I just recently learned (at 14 lol!) that part of the reason my ds has never liked answering that question is that when he's done with his day at school and we're driving home (which is when I ask) he has literally cleared his brain of any thought of school for just the time being and he's thinking about other things, so when I asked him what he did, he actually doesn't remember. It's not that he's got a memory challenge at all and it's not that he dislikes school (he actually loves his school) - it's just what's up in his head at the end of the school day. And each of my kids is basically the same about this - including my youngest who practices on a gymnastics team and also hates me asking about what she did today at the gym when I pick her up - again, she literally, in the moment, can't remember. I can, however, go back and ask them after they've been home awhile and had a snack and we have much better conversations at that point in time
Best wishes,
polarbear
