Good job keeping your cool. Honestly i'm not sure i would have. Not to say i would have drawn, but i would at least have asked him what the heck that was all about. Of course, i'm a young hot head that has a lot to learn.
But i think you did the right thing. Especially leaving when he was coming toward you at the pump. Not much tactical advantage at a gas station. Especially when there are other people around that could get caught up in the hypothetical crossfire. All in all. I think it was a good first carry. Just because you have it doesn't mean you have to use it.
