Mine did that once. He was new to us and about to start shed(eyes clouded up the next day) so he was a little cranky and he just kinda lunge-jumped out of my hands at my fiance and fell to the floor. Also, when he comes out of his hides to explore at night, he likes to climb to the lid of his tub and circle it while peeking out at us or the TV. Sometimes he loses his grip and you'll hear *THUMP* I try not to anthropomorphize them, but when that happens it's almost like he pops his head up to say "I'm good!"