My RB cat Y.Lee did that. His favorite places to love bite you were on your chin (preffered by me) or your nose (could be a little painful)
I recall one time when sweet Y.Lee needed to stay over at the vet's. I went to visit him (and I have NEVER seen a cat more happy to see a person than Y.Lee that day). He was in a cage at eye level, so I could open the door and put my head right in the cage with him. He gave me a love bite on the nose but instead of his teeth being on the larger part of the nose the lower canines actually went INTO my nostrils. OUCH And the worse part was, when his teeth would be on the larger part of the nose his mouth would have been still opened and he would let go quickly. In this intsance his jaw closed all the way. This made it more comfortable (for HIM) and he did NOT let go right away. Well, the poor guy was sick and in the hospital, I couldn't very well yell at him, so I had to pry his jaw apart so he'd release me. double OUCH