This. Just happened to me a few weeks ago. When I ignored a greeting from homeless man as he passed me on strip shopping mall sidewalk, he turned and stated "I'm going to f... You up!". My response? I placed my hand on Bodyguard in pocket, but never brandished and walked quickly to my car leaving the shopping center The result? He followed me across the street to BP. At that point, informed store manager what had happened. She told me how nice he was and went out to speak to him. He left the store area She said he was having a bad day.
He was nuts.
Well, from what happened to you it seems like you would have been justified to pull your gun seeing that the guy said he "was gonna **** you up" and started following you..........