H.H.
My daughter did this same thing around 2. I was hoping to potty train then also, but didn't b/c of this. It seemed to start when I started introducing the potty. She went regularly so I didn't think she was constipated or had a blockage. The dr did not seem concerned and she just grew out of it. With potty training, when she acted like that I would just ask if she wanted to sit on the potty and try to go and she always answered no. Might just be that he's becoming more aware of what pooping feels like. She was potty trained by 3. I didn't push it b/c I've heard of kids needing to take laxatives and stuff b/c they get so anxious about going on the potty. Good luck!