Hope you filed a report ... I would have and have done so in the past. Is sometimes trouble but if am going to be in trouble for reporting the truth ... So be it.
Funny enough, the guy had a bumper sticker to call 3-1-1 and report driving. So, I did. The car was unmarked, so I didn't see the "cop lights" until I caught up with it at a light. A couple of weeks later, I get a message from a "duty sergeant" to call and talk. I never called back. Something about the tone of the message just didn't sit right with me, so I never called back. I should have, and have kicked myself since.