Wrong on all accounts: I am indeed a non-native speaker, and reading it again I do see a few indications myself, and my definition "hostility" (and I'm sure I am not alone on this) is a spectrum so you are also giving yourself leeway to interpret things in your preferred way, for example furrowing your brow for a couple of seconds and then looking away is a hostile behavior, if you get on the train and look a stranger like that they would likely describe you as "a bit hostile", maybe I am using it too much as a synonym of "aggressive", which according to the dictionary it is, if instead I were talking about war or politics it would be crystal clear we are talking about the "hard" flavor of hostility but here we are talking about a simple client-customer interaction to get some food.