If you both have oral herpes, statistically, it's hsv1. Oral herpes hsv2 is rare. When oral hsv2 happens, it rarely recurs, so if you are getting recurrences, it's most likely hsv1.
Assuming it's hsv1, you already have antibodies for it, so the chances of you getting it in another location are very, very low.
She didn't break the skin, and the skin on your arm is too thick for the virus to penetrate if it's not broken.
There's really nothing for you to worry about here. If she had broken your skin, maybe, but even still, you have antibodies that would protect you.
I wouldn't worry about this at all.