The meaning of stalking

Isn't that when you go on a date but the other person doesn't know it's a date?

I once posted this on social media and several months later I got a message from a guy who had a thing for one of my roommates that said, "on october 9, you posted something about stalkers. I was wondering if that was about me." It wasn't, but the fact that he had to ask should have told him something....