Has this ever happened to you?

Last month DW and I were heading on the PA Turnpike for home. A single occupied vehicle started tailgatting the RV at 65 mph. I was at the speed limit but slowed down very gradually and the guy gets closer and closer, and and doesn't back off. I then slowed down gradually using the brakes, thinking he had cruise set and didn't realize that I was slowing down to get him to go around or back off. He doesn't, he gets right on my license plate. I sped up and get room between us and then there he is again. I slowed down hard thinking he would go around and instead he goes right up under the rv, so now I'm scared, thinking he's obviously a nut case. I'm watching on the rear view camera the whole time, we didn't have the towed for the trip. I have an exit coming up for a service plaza and signal to get off, and start up the ramp. Nut job follows and I then stay on the 'pike (wouldn't you know there was no Troopers in the plaza) and he follows right back on, and then I veered back onto the ramp at the last second, and he didn't have a chance to follow. This had gone on for 15 miles or so, and this was on a section of the 'pike that's really pretty empty and barren for quite a few miles. I had slowed down to 40 for a bit and then sped up, more than once, so the individual was obviously playing some kind of game in his own mind. I was not a happy camper.