I suspect, based on my own experiences and her continued use of the word 'skirt,' that her issues are based on her expectation that kilt wearing is equivalent to cross-dressing, and she's upset that her image of you is in conflict with her image of cross-dressers. As with most of the others who have posted, my advice would be to meet with her, discuss it, and find out what the big deal is, in her mind.

Good luck!