I think it's part of the social contract when working in a coffee shop. You're in public, drinking coffee, and people need to use the restroom... It's OK to ask

I think it's part of the social contract when working in a coffee shop. You're in public, drinking coffee, and people need to use the restroom... It's OK to ask people for help. Getting upset at something is similar to people getting upset when they're bumped on public transport. You're in a cramped space, that's moving, and that people are entering and leaving, what else would you expect?