He actually apologised for being invasive. He admitted to having looked up all our neighbours too. He also realized that it was his gf who had told me, he said 'looks like I've got a spy in the house'. As if he didn't know his gf and I were talking. ...Weird.
Anyhow I still don't know what my opinion of him is. I can't really understand if it's friendly harmless flirting or if I should be very wary of this guy.