There's a risk of passing on HIV through any body fluids but fluids like saliva provide a negligible risk. If you know the lady, I would ask her to get tested and if you believe she could be HIV positive there are steps you can take up to 72 hours after your possible infection, but the posibility of getting HIV from your actions are actually really low, but to answer your question, there is a risk (just a very, very small one).
You need to get tested in 4 weeks and again in 3 months if you think you have an infection - the results at the clinics are totally anonymous.
I wouldn't try to worry too much though, but I've been in your situation (or am right now) and it's kind of impossible not to.
This is a pretty poor excuse for professional help. If you are THAT concerned then you should see a doctor and discuss exactly what happened and what your risks are. I don't mean to sound rude, but this is your life we're talking about and I would strongly suggest that, if you don't know the girl, and there you are worrying so much, that you go see a doctor.
He/she should be able to clear up any questions you have.
What I've been trying to say is that you have a very low chance unless the abovementioned "Unless there is fluid in contact with fluid / mucous membranes / open sores etc"
go to the expert forum and look at the previous questions don't make a new post a nd waist $15 of your money and the doctors time just read the previous answers for similar questions you will see that the doctors on this forum say that masterbation (masturbation) is ZERO RISK.