The chances are most likely low, but I wouldn't be able to say for sure. There is pre-cum, and that can lead to pregnancy-it's not probably, but it could.
Just wait it out and try not to let her stress about it. Keep her mind off of the idea until she actually misses a period. Stress can delay her period, causing panic.
If she misses a period, I strongly urge you to go with her to the store to get a test and be with her when she takes it. It will make her feel a lot better knowing you are there for her.
Please, please, please get some condoms.