I think the OP is lucky he didn't go to jail for "brandishing" a gun. I hear a lot of stories on the new where in a road rage someone flashes a gun and get felonies.
NO. In Texas this is an almost textbook case of what CHLers are taught to do.
* He did not instigate.
* He actively attempted to avoid.
* He kept a barrier between himself and the BG and attempted to calm the situation.
* He did not show until a further escalation wherein the BG was attempting to enter/open the vehicle.
* He left as quickly as possible and likewise called 911 as quickly as possible.
Pragmatically, absent other information, its hard to see what better method he could have done.