I have had the power go out at my house and the temp inside my incubator fell to 70 and stayed there. I'd say the power was out for like 1, maybe 2 hours. I was really concerned and freaked, cuz of all the baby geckos.
So I called up one of my breeder friends and talked to him about it, and he said there should be no harm done and not to worry. The power came back on and the incubator went right up to the temp. its suppose to be at. 
And guess what....since that power outage I have had 4 baby gecko hatch out of that incubator with no problems and no flaws. They are just perfect.
I really dont think you have nothing to worry about. If you want to know who I talked to, send me an email and I'll let you know. If you have any other concerns you can call him and he'll put your mind at ease. 
Shayna
Leo Lovers Lizard Lounge