You know, that's an extremely good point! It's been hot and dry here lately (which is saying a lot since we are in the Pacific Northwest) and I had noticed he had gotten just a little constipated a few weeks ago, but quickly remedied it by sprinking water on his food. He's well hydrated now though. :) He actually started pooping twice a day this past week and the second time is mostly completely water. I'll give some things a try, starting with a humidifier in his cage.
I also think I will reduce the amount of time the heat lamp is on, as I just realized he has been nose rubbing and he hasn't done that since he lived at the school, over 2 years ago. He has also been trying to get into my sewing "closet" that is much cooler than the rest of the house. This all makes sense now. Low humidity, too high of heat.
Thanks so much!!!