Herpes only transmits from direct skin to skin contact from the site of infection. So even if she had oral hsv2 - statistically, it's far, far more likely that it was genital - this wouldn't transmit anything.
If she has genital hsv2, you'd have to have direct, unclothed skin to skin contact with her genitals, and a lot of friction, usually the kind associated with intercourse.
If she has oral hsv2, she'd had to give you oral sex. Also, oral hsv2 rarely sheds the virus, rarely recurs, and very rarely transmits.
I wouldn't worry about this at all, and would be grateful that she was honest with you so you could make an informed decision. :)