Why would someone do this to me when i was driving?

So i was headed home from the movie's tonight and i ped some guy who wanted to do 40 in a 60 and then after i ped him he wanted to tailgate me so close that i couldn't see his headlights and he followed me home and thank god i live in a gated community but i don't understand why he did this it scared me shitless to the point that i called the sheriffs office.