My hamster's is all wet (w/out poop) does she have URI?

I bought my female, teddy-bear hamster on Saturday afternoon. She was in the car for about 2 or so hours. I put her in her cage at home and left her alone for 24hrs. Then the next night (once the 24hrs were up-- Sunday night) I took her out. She was jumpy but other than that, she was perfectly fine and docile when being handled. Then tonight (Monday night) her is all wet and it looks like she has no fur there but I think its becauase it's all wet. Is it because of stress? I plan to leave her a lone for the next few days. Any ideas what it is? If so, ways to treat it? (She is less than 5 weeks old and also, today my room was really warm because I put a heater in it. Could it be that she was just sweating?)