I have seen women of various nationalities exposing far far more than what the OP says she did, and never getting any flak..Perhaps the lady was just in a bad bad mood. Or maybe it was one of those "straw that broke the camels back" moment. She was prolly just cheesed off with all those ladies who she felt wasn't respecting the culture hence chose you of all the people to vent. Either ways I do feel ya on how annoyed you must have gotten. I know PERSONALLY how that feels. Just take comfort in the fact that in all these four years it just happened to you once.And that the woman didn't turn out to be too abusive..and kudos to you for being patient and dignified in how you reacted.
And PS as a Muslimah I never feel it's right and just to tell a non Muslim how he/she must dress. Provided they are not breaking any laws they have all the right to dress as they wish,period!And even if it's a fellow Muslim, then I will only convey to them what Islam says, in case they are unaware, and then leave them to decide what to do.