Wendy, as sucky as this situation is, I suspect that gal was jealous/envious because you have the confidence and beauty she hasn't been able to find in herself. Maybe it was even subconscious on her part.
As far as arms go, let me say that I actually wish my arms were bigger. (I carry all my weight in my lower body.) And, as luck would have it, I've had people make comments to me about having a "stick neck" and "stick arms," etc., (not something I can change). I think those folks are just trying to make themselves feel better at others' expense.
Anyway, I just think this person would have had *something* rude to say not matter what - even if your body was totally hidden, she'd probably have something critical to say about your voice. She's not at the same place you are maturity-wise and emotionally, and that's too bad for her.
Of course, if you see her again, and she says "Oh you have big arms" you can always say "Yes, the better to PUMMEL you with." <img src="/images/graemlins/wink.gif" alt="" />
