Legal compliance is not equivalent to courteous driving. The other guy may or may not have been a jerk, but there are also plenty of plausible scenarios in which you were also the jerk, even though fully compliant. e.g. rapid acceleration, scary engine rev noise, aiming the vehicle towards the kids as they were moving off the street. Not to say you did any of those things, but I just wanted to point out that being within the law and not-being-a-jerk are somewhat orthogonal .