Hi Sharon , I would say the same as Doghouse135 and Tarcus, it's either a combination or one of two things, the drop in temperature (I know yours are indoors) and because Chris is not there.
All mine are indoors to, and it's lovely and warm inside for them. Even so some of mine love their time sitting on towels on top of the radiators, as if they are cold. But I'm sure they are aware of the change in seasons outside. Star has been very busy stocking up her nest tunnel. It's pretty much packed now, so she only comes out very briefly a couple of times a day to have a drink and a bite to eat. She used to spend lots of time on her wheel but for now she hardly looks at it. I've checked her out, and she still looks lovely, with a nice coat, and bright eyes, so I'm sure she has just slowed down for the winter. So has Pickles and Chloe, but the rest are as bonkers as ever, that's chippies for you.
They can get very attached to their owners, when I went away first mine actually sulked when I got back. Some of mine treat me as if I am their territory, and will chase others away from me. So even though they may not like being picked up, or want to sleep in your lap, they can still have a strong connection to a human, but always on their terms. Some similarities to cat behavior here. As Chris has spent the most time with your two chipies it's likely they are missing him in some way.
So I think you are not fully accepted as part of their colony yet, they know that winters here, and they have a different routine this week is all the problem is. Interesting creatures aren't they, but Chris should stop hogging them to himself and let you have a more time with them
