Their nose should be dry & free of debris, if it does start running & they seem to be breathing alright, its probably just a cold. (You should keep them warmer, (not to warm though), & give them plenty of water & food.)  *A Vet. visit should be arranged as well!*

 *do not give them their dust bath while their nose is running. That will cause problems by getting stuck to the nose & will make it hard for them to breathe