The best way to handle being kicked out of places that don't like you open carrying is to look forward to it. Hope that you'll finally get booted out of somewhere. I've found it to be extremely rare, since it's only happened to me one time. By looking forward to it, you'll be pleasantly surprised when it finally happens. It nothing more than a milestone of progress to be made while OCing.
You did your best to inform her what the laws were, and you left when asked. You shouldn't be irritated, because it appears you did everything right, and you have identified a business to be avoided. Good job.