No. Well-behaved should be the norm and, if they are, I wouldn't notice them. However, if I have occasion to interact with children who are particularly charming, bright, perceptive, talented, humorous, etc. I will compliment them on that.
Way back when I was acting, I did an episode of The New Munsters (it was work -- what can I say?). Eddie Munster was played by a very young actor -- he was, I think, around 10. During a break in a scene that involved, exclusively, day players like myself and Eddie Munster, I noticed that all the "adult" actors were talking with each other and the boy playing Eddie was standing by himself. I went over to him and said, "I'm really impressed with your performance. You're a very talented actor." He smiled nicely and said, "Thank you very much. I think you're very good, too." We chatted for a bit and the interaction was, in every respect, indistinguishable from that I would have with any adult actor. He was a very impressive young man who deserved the compliment.