What's a Mom to do?

So while talking with my family today I was reminded of a situation that happened around 2 weeks ago when my husband, daughter and I were at the DMV taking care of car registrations. While my husband was at the counter I was allowing Savannah to run around and see everything. There was a little boy there a few months older than her. He was very interested in Savannah and came over. He came up to her and looked at her and then pushed her down. His mother was instantly apologetic and pulled her son away. I didn't think it was too big a deal. Savannah wasn't crying and got right back up and walked back over to him. I was very surprised as she can be extremely dramatic at times. Instead she walked over and put out her hand to him. I thought, Oh isn't that sweet. She is so forgiving. Boy was I wrong. As soon as he put his hand in hers, she snaked her fingers up the back of his arm and pinched him as hard as she could. She then proceeded to smile at him and walk away. I was so shocked. I started to apologize and the mom got her son (who was howling by the way) and went back to the other side of the DMV. I wasn't and still am not sure what to think. On one hand I am appalled that my 1 year old sweet angel even understands that pinching hurts. But on the other hand he did push her down. I have to admit I didn't discipline her for it. I was too busy laughing after the mom and son left. I mean I know she shouldn't hurt others but he started it right?