Did you have UFO installed? A couple of other people have reported the same bug that does not disappear when UFO is removed.
I am using UFO - at first I thought this happened to my steward, but I worked out that after I made her steward I had to talk to her again and tell her "it's time for us to part ways". Then when I spoke to her again, she had the steward dialogue. I don't know how it works without UFO, but it seems that for me with UFO, when you make a follower a steward, they are technically still following you (although they stay at the house) until you dismiss them via dialogue.