We can refer to the whole concept of you just being another face in the crowd and they have no idea who you are or your intentions. So in the current environment of more public violence and increased tensions between gun/no gun communities, I'd suggest that you have an equal responsibility to announce your presence and intentions to set some expectations before you just stroll up to the counter and start going akimbo. If I've made inferences into how the situation played out, then some more contextual explanations may be necessary.