My son is honest.....

My son made me so proud the other day I just had to share but there is a discussion in my story.....
I took my kids to Mcdonalds with my sister-in-law and we were walking out the door to leave. I was riding with her because she had a van and then I wouldnt have to take the truck. We were having a great time and when we got ready to leave my son Zac found a twenty dollar bill laying outside on the sidewalk. Well he picked it up and told me that we needed to go back in the store and give it to the manager because someone may be looking for it. I said ok and told my sister-in-law what we were going to do. Well she got all upset and told me to just keep the money and come on. She didnt have time to wait and that she needed help getting the kids in the car. I said ok I will help and then Zac and I will go back into Mcdonalds. Well she made a big deal about it and said that I better hurry up. She couldnt wait on us and if we werent back in ten minutes she was leaving. I said fine go ahead and leave just let me get my kids out of her van. Zac wasnt leaving until he returned this money and I wasnt going to try and stop him. So she sulked and pouted but waited on us. So Zac took the money to the manager and we told him that we had found it outside and my son wanted him to keep it if someone came looking for it.
As we were going to my sister-in-laws car this older woman comes dunning over to me and hands me her phone number. She said the next time I wanted to take my kids to Mcdonalds she would buy them all happy meals. She saw Zac hand the manager the twenty dollars and was happy that someone had found it. She had dropped her purse on the way inside and some of her stuff had fallen out. She showed my her bank information where she had taken out some money. She said when she counted it she was missing twenty dollars. She asked Zac why he returned it and he said because mommy says you shouldnt keep something that doesnt belong to you. Its wrong and selfish and you need it more than I do. He smiled at her and said money doesnt grow on trees you know. She reached over and hugged me and said you should be so proud of your little boy. I looked at her and just smiled.
My sister-in-law thought it was stupid to return the money and a waste of time. She compalined the whole time about it. How we wasted her precious time on something so trival as that. I should have just taken the money and kept it.
But if your child asked to return something wouldnt you have dont the same thing. I mean everything I have taught him for the last five years is starting to show. Her kids wouldnt have dont that but her kids expect the world to bow at their feet. I think what Zac did was wonderful and I wish all kids were like him.
Dont you instill honesty in kids, dont you teach them not to steal or keep something that isnt theirs.
I dont know, maybe I am doing something wrong but in my heart I know Zac is on the right path.
What do you think?