Thanks for the replies guys, they made me feel better--Kayann and Micki, yours made me laugh

My husband called the mom at work, and she said it's fine. Her husband was in a major hurry this morning, and he felt bad for not talking to me after it happens. She also said that her daughter does need to learn her lesson, and she's glad it happened with a dog that she knows, and she knows is healthy and up to date on all shots. She also said if we want to work with him on getting him used to kids, she would bring her over to the house and let them play (he's much better when he's not on a leash).
My husband also told her that if she would have needed stitches or anything like that, we would have paid for it.
The mom is sure that the girl will just brush this off, she's a pretty resilient kid, so I guess all is well.
I guess I can drop the silent treatment now