[CLIENT] Client Notifies Me of A Friend Coming Online that Isn't On My Friends List

I keep getting this notification of sum29742638 coming online as my friend, but I have no idea who this is. I'm not sure if I've been friends with this player or not, but they aren't on my friends list right now. Attached is a screen shot of my notification client and a search in my friends list for this player and there's no results.