According to a friend who works in subrogation for American Family Insurance, it shouldn't have much of an effect on your policy if you have a good agent that is willing to sort of "gray" the claim. A decent agent won't lie about what happened but can word it in such a way that you won't be penalized. In any event, it's unlikely that a minor incident will cause an increase in your rates, unless you have a history of minor incidents.

**Another edit - the friend said in general, if the accident causes less than $1,000 damage, it won't affect your policy. It also doesn't matter who was driving, as long as you gave her permission.
You might want to add your GF as an occasional driver to your policy just in case this happens again. For my insurance at least, it doesn't make a bit of difference for my rates.
It's also possible that if your agent is a pain in the butt and won't work with you that you simply don't make a claim for the damages - pay them out of pocket and the insurance company won't have a clue what happened.
**I meant to add, tell your GF not to panic - I've been in two minor accidents in my life, and each time I got so worked up that what I put myself through was fifty times worse than what my insurance agent or the police did to me. It's easier said than done, but remind her that SHE is more important than the car or your insurance rates - it would have been far worse if she had been injured.