Hm, now that I think about it, can't "pooping" be a sign of nerves? Being nervous? It is with other animals. Could it be that the handling makes her worry/nervous and she poops because of it?
I remember seeing something from Justin Kobylka where he theorized that they hold it as long as they can, because in the wild, if they go in a burrow, they'd have to find a new hunting ground. The prey would avoid burrows that smell like snake.