Admit it people. We all do it. Gossip is part of human nature, no matter what kind of person you are.
I try and refrain from doing so, but sometimes if a person is brought up in a conversation, we just talk about them. I'm sure people talk behind my back too, but honestly I'm not that bothered. At the end of the day, we're all friends. So long as it isn't anything crude or hurtful, then it's absolutely normal and expected.