I am not a tortoise expert by ANY stretch of the term....but I wouldn't think his light going out just for last night would cause him to come down with an illness already by this morning.
Hopefully someone with more tort knowledge will step in soon to give you better advice, but for now I would say to simply make sure he is nice and warm, and make a vet appointment first thing Monday morning. As long as he is still eating and active, he'll probably be fine until tomorrow.
Depending on what kind of enclosure you have him in, I'm guessing that since you are in Ohio, it may have been getting a bit cooler than normal in his enclosure, I know I've had to "up" my heaters a bit in a couple of enclosures, the Iowa winter has been kicking in here. Double check to make sure he's got proper warm temps, with an accurate thermometer.
Good luck.