Does someone know if I unfollow them on facebook?

[Cassie]

You can safely unfollow them. There are no notifications about that unless they use Social Fixer or some such.

The reason you were suddenly "following" that person without remembering you had followed them in the first place, is most likely that you used to be friends, and the other person removed you as a friend.

It could also be that you have requested to be their friend and they hid, deleted or ignored your request. That would make you a follower too.

So there is probably no chance they would be offended if you stopped following them. Chances are they don't know you're following them and might not have intended for you to be a follower.