As long as the temps don't stay that low for a long period of time (a day or more) than it should be okay. If it happens alot, an RI could stir up. Just check the heatpad often if possible. Which side does he lay on the most? What you could do is buy those heat packs that are used for shipping (there are 20 hour and up kinds). You could put one of those under the enclosure when one of those power surges happen, if you can. The only thing you have to be careful of is those can get 110 degrees on the spot, so wrap it up in paper towels and put it under the tank. That might help.

That sucks, I hope they don't happen anymore.

Jennifer