I don't know really where to post this, so if this post is not in the correct place - sorry.
I encountered a very suspicious person. At first I invited him to a group to do the same quest as I am on. He neither accepted for declined and proceeded to walk around and kill mobs. I tried inviting him again after the period of waiting for a response expired. Still the same outcome.
So I started asking him random questions and saying hello. No response whatsoever. Didn't even stop walking and killing mobs. I don't know if this guy was just anti-social with me, but I thought he was suspicious about it. I might be wrong though.