I recently adopted two kittens, who are 3 and a half months old. They seem to be doing really well - they are very active and social and their seems to be no end to their appetites! However, a couple things concern me: first, when one of them smells something (like if she is smelling my hair, for example), she sounds really sniffly - she doesn't seem to go around sniffling constantly, but I notice if she is purposely checking something out, she sounds sniffly (while the other kitten does not). Also, they both have had something brown in their nose - at first, I thought it was dirt or canned food - I wipe it out of their nose, but the next day it is back. Is it common for kittens to get stuff in their nose like that, or could it be a discharge indicating illness?