I was thinking that one possibility was that B behaves passive-aggressively and that the situation in the cab was one where B finally lost it (for no reason). I have no idea what the context is, but I thought of romantic feelings because they sometimes explain otherwise inexplicable behaviors. Again, I don't know what the context is and it was just an idea. To return to your original question, A does not seem to have acted inappropriately. And I hope that A gets over this soon.