What would you do if you were in this situation (details inside)

Suppose there is a forum you really like. You have a lot of friends there. People there like you and are generally nice to you.

Except there is a user who seems to like you a bit too much. They occasionally send you messages wanting to get close to you. Their messages are nothing threatening or creepy, just general greeting stuff. But they would include things that are a bit too… specific, like things you only say in passing on the forum or things only people who know you well on the forum know. It is clear to you that this user has been doing lots of research about you and have been reading your posts quite extensively. You don’t know how much they know about you, but you have a feeling they are constantly looking at your posts.

Would you feel uncomfortable? What would you do in this situation? Would you stop going to the forum? Would you just ignore the person and continue on the forum like nothing has happened? Or what else could you do?

I was reading a horror story and this is the main plot point of the story. I just think it would make a good discussion.