I've had that same jumping thing happen with Western Red-Backed Salamanders, Plethodon vehiculum. I was looking for Dicamptodon along a stream bank when I found a large vehiculm (2 1/2-3") under a rock. When, after looking at it and taking photos I went to go return it to its little hideout, it promptly flipped into a small waterfall and I though he had drowned. It turned up unscathed on an emergent rock a few moments later. It's well known that most of the western Plethonids are capable swimmers, but Aneides? That's pretty cool, I've never heard that before.