Total regression

Ok moms, I need help. Ben was so excited about the potty and loved the dancing that followed each success. However, all of the sudden the phrase of the day is, "no poo poo in the potty!" He'll still tell me when he has to go (although more often its while he is in the process of going in his diaper) but he refuses to get on the potty. So what happened? Why the sudden aversion to the potty? I'll take any advice.

On a completely different topic, thanks to Dave and Mary for hanging out with us last night. We had a great time.