Had nearly the same thing happen to me. Small suburban 2 lane..me going the speed limit and the psychotic plague infested guy in a BMW crossover instantly pulled up within 10 ' of my bumper....could see him doing the "Italian" both hands in the air....so started off a volley of salutes...I started having "the finger" cramps...got bored....pulled over to "meekly" let him by....got his lic. plate.....and as a good concerned citizen called it in.
Passed him stopped by the State Police 6 miles down the road and to his credit his was communicating the same way with the officer as he had with me. Passed them and waved real friendly....you'all all come back soon..ye hear?