It could mean they have a URI or maybe a cold or allergies or... I feed them off p/k to my snakes regardless.. however.. if they look sickly, I wont even buy them. Sometimes around here you have no choice but to buy a rodent that appears that it may be as mentioned above. Even at that, the few times I got rodents sniffling and sneezing, there were no adverse effects. I would not worry about it.