There is what they call a tail pocket, where (and those that have experience, correct me if I am wrong) there is actually a indention that causes the collection of and bacteria at times this can get irritated and sometimes infected. Bella doesn't have a pocket so to speak of, but she has loose stools quiet often and wet gas, so she will collect debris up underneath and it drives her crazy. We keep sensitive baby wipes in the family room. (that is the door she goes in and out of) and if she is twirling around or scooting, that is my clue to wipe her. Bullet might just have the same kind of tail, one that collects. Keep an eye on it and have some wipes or something to clean it with when it happens.