Guy driving in parking lane cutting off cars, gets instant karma

[Aristus]

8. I don't know who was the asshole, me or the other guy.

I was driving down a one-lane road a couple of weeks ago, and a guy ahead of me was going very slowly. I'm talking like 15mph in a 35 zone. There was no one ahead of him. He had been driving at a relatively normal speed until I drove up behind him (not on his bumper, like a dick; just behind him.) He began slowing down, slower, and slower, until we were practically crawling along. I didn't want to cross the double-yellow to pass him, because it's a road the cops patrol frequently. Finally, a left-turn lane came up, and I moved into it, sped up just enough to get past him, then returned to the driving lane. Technically, this was legal, since I passed him on the right.

The other guy must have gone berserk, because he hit his brights and came up right on my tail as fast as he could. I drove at the posted speed and prayed he didn't have a gun. Finally, we reached a two-lane stretch of road, and I wished he would pass me now that he was able. But he didn't. He kept on my tail the whole time. We finally reached the freeway on-ramp, and he peeled out ahead of me, roaring on the accelerator like assholes do, and made his way up the freeway, swerving in and out of the way of other cars until he disappeared into the distance.

Who is the jerk? Was it me for taking a step to get ahead of someone who was deliberately slowing me down? Or him for being a dangerous road-rage-monkey?