So. Ca. here. I had a similar experience in my outside enclosure last year. Several Sand Lizards and Blue Bellies hibernate outside in the pit. All were in hibernation when we had a couple of significant down pours in one week. The pit filled up anywhere from 2 to 6" of water, depending on the location in the pit. It was like this for hours upto a day or so before I got the sump pump going. I assumed all were lost. But then when spring came around, all the animals were back and kicking, even that year's offspring. Even had the two zebra tails appear again. Can't explain it either....weird?!

Roger