How would you handle a situation that you never came across before? It involves my 6 year old granddaughter?

My wife and I took our 6 year old granddaughter out last Friday night to the local mall to find her some new shoes for spring. As we were walking around, she spotted a big dog with it's owner and we could tell that this woman was blind. She did have another human companion with her for support also. My granddaughter yelled and pointed, "oh look at the dog!!" and started running up to it. I quickly grabbed her and said, "sweetie, you can't pet this dog". Well, she started to cry because she loves animals and could not understand why should could not pet this one. We found a place to sit and tried our best to explain to her about these dogs that they are "working" and can't be distracted. It was very difficult and my wife and I tried our best and we hope we did ok. Our granddaughter said that she understood, but we are not too sure. Would you have done the same thing? Thank you very much.