I have one corn snake that has regurged a few meals. They were a weaned pup, and about 4 days later, we find a glob of fur and a tail. and last week he had 2 wk pup (all we had). I haven't seen anything in his tub, and it was only 2 times he's ever regurged.
This was within the past month too, and we were feeding frozen thawed, so we would give him the smallest weaned we could, but the pickins were getting slim.
We thought it had something to do with the temps when it happened, but I'm more positive it is the size of the prey. Our guy just couldn't handle the larger weaned size yet. I always think the prey is to big because of the size of their head, but I know it should leave a small bulge, so I figured it was fine.