One other perspective to consider: if when you turned to look at the driver he/she wasn't laughing at you, then I would be unlikely to attribute it to malice. Perhaps the driver was anticipating racing around you, or simply hit the gas hard by mistake. I bought a new pair of shoes recently and the first few times I drove with them my starts and stops were a bit abrupt as I got used to the new soles stiffness. Just some thoughts. You did an excellent job handling it.
This is a good point that I also considered, especially since there was no additional harassment. Still, it seams less probable considering the timing of the acceleration, and how close he got to me, with no leftward movement.
If I turned (I didn't) and seen the driver laughing, I'm pretty sure things would have gotten ugly.