When this type of situation happens, just let it go and keep your blood pressure down. All this does is instigate a confrontation and a possibly put an innocent person in great danger; which could be anyone of us. Unless there is a crash, it isn't worth your time to prove your point to this meathead. You'd be surprised how many people aren't paying the least bit of attention to what they are doing when they are driving a vehicle that could do major damage to the people outside of the conflict and then you are in deep doo-doo whether you are right or wrong in your own mind. I am surprised at how many people change lanes on the freeway (65 mph+) right in front of me leaving about a half car length between us. I just take my foot off the gas, slowly back up and keep driving. I've even had that person flip me off and start doing the brake tapping thing because I am right behind them. I'm not trying to be a martyr, because I have had my fair share of flipping people off which leads absolutely nowhere. However, escalating the situation to the point where both parties are pulling over will never solve anything. Both of you think you are right and will never back down. Sometimes, I think our cars instigate a lot of people think we are going too fast, even if we are going the same speed as everyone else. Long response, but next time just ignore it, keep your cool the best you can and go about your daily routine. HAPPY DRIVING bro!