Contacting genital herpes is very possible even when she's not having a breakout (even the commercial for valtrax says so). However, it is less likely. Be sure to use proctection and avoid contact when she has a breakout. Don't let hormones get the best of you, if you contract this disease, there's no getting rid of it. Just be safe.
And don't listen to pretygirl07, I've been reading her otehr advice on other questions, she does not sound very educated in this subject what-so-ever. :)