OK, so I just let my rats out for their normal play time in the bathroom. I usually carry them from their cage to the bathroom on my shoulders, and normally they can't wait to climb down and play. One rat, Scrabbles, acted normally while the other rats, Checkers, acted strangely. When I got to the bathroom, he wouldn't climb down off my shoulders. I put him on the floor, and he seemed extremely bothered by Scrabbles attempts to play. I shooed the other rat away, and Checkers walked up against the wall then stood very still. He was also still puffed up, as if he was agitated. I put him up on the laundry basket, so he could get away from the other rat, but he still seemed scared. I gave him a treat, and he took it, but it took several minutes before he was calm enough to eat it. He eventually started gromming himself and walking around slowly on top of the basket. I tried putting him on the floor, but he squeaked when I picked him up (which he hasn't done in a long time), and after spending a moment or two shocked on the floor, ran back up onto my shoulder. What's going on? Could he be sick? He let me feel him all over, and I didn't see or feel anywhere he was hurt. Or is just having an off day?