This happened to me too. There was a guy on Reddit looking for help setting up Plex on a dedicated server. I run a small chat room and helped him out in there.

This happened to me too. There was a guy on Reddit looking for help setting up Plex on a dedicated server. I run a small chat room and helped him out in there. But we did exchange a few emails. I use fastmail and he uses gmail. A few days later he pops in the people you might know thing. At the time I did not have a cell phone so I am assuming he gave the app access to his contacts or something. I think it is safe to say Facebook has a pretty detailed profile about you even if you never made an account.