Grapes, raisins, and even currants are very poisonous to dogs. Whenever your dog ingests these or any other poisonous food, you should contact your vet as soon as you can for professional advice. Ingestion of even a small amount of these items can result in severe, acute kidney failure and/or liver failure.
If she has a healthy liver she should be okay, however you should keep an eye on her. Some dogs react and some don't. Things to look out for a lethargy, vomiting, pacing, and extreme thirst. Or if you just notice anything out of the ordinary. If any of that shows up call you vet and get her/him in.