People are probably not being as dismissive as you think. Your son probably looks like a 4 yo and moves like a 4 yo and therefore he gets treated like a 4 year old. It is impossible for people to know that your child is gifted. The questions you say they ask are appropriate. I could see myself asking those questions to a 4 year old.
I do understand you irritation though. My babybear is small for her age and Gifted. So, though she is 7, she is the size of a 4 year old with a very large vocabulary and advanced thought processes. It is very frutrating.
What I have done for babybear is explain to her that not everyone understands that she is much "bigger than her height". It isn't always easy. As Mom, I just try to make sure she knows I understand her and I encourage her in all the wonderful things she can do.
Best of luck!
