Pain in neck, back, and shoulders often doesn't show up until a day or two later. Get to a Dr. or if you've got a good one, a chiropractor.

OTOH, I was listening to "Car Talk" a couple of years ago and one of the guys said that he was once riding as a passenger on the Autostrata in Italy. His car got seriously cut off, requiring locked brakes at high speed. He asked the driver who was as cool as a cucumber, "aren't you angry at that jerk?" The driver answered "No. You see, today he cut me off. Tomorrow I cut HIM off!"