Mine leap up, too! I was going to say watch out Billy doesn't get your little girl instead of the mouse, then l noticed she's feeding him through the little door, which should protect her :-)
Squidwood surprised me at his last feed, too. He does strike and constrict, but this time he leapt out of the feeding RUB, so that most of him was out on the ground, then wrapped the mouse and the kitchen towel together! Cue me, trying to extract the kitchen towel from between his coils and the mouse...he wasn't best pleased!