First off, congrats on your observation skills. Thats 99% off getting a**holes like this guy off the street and keeping yourself safe. Don't let this guy chase you out of your riding spot. A license plate number would have been a huge help to the police. I hope they look for him. If this ever happens again, make no secret of the fact that YOU see him. If you have a camera on your phone, take a photo of him. Most guys are trying to act tough in the safety of their car and want to try to make you uncomfortable. I would let your friends in the area know about the car. Find a friend to ride with for a while if you are feeling uneasy. It's no fun to be looking over your shoulder all day.