Co-Worker changes to Friends With Benefits

We started as co-workers and then became good friends. After a drunken night at his house we had sex and have since become friends with benefits. We are friends before anything else. It's not weird or anything and we are on good terms. I think if we ever do stop we would still be good friends. Just be careful if you do decide to go out with a close friend because sometimes when you end things you leave both types of relationship at the door.