It apparently upset you enough that you are still lamenting over it five days later.
Some people have no volume control. End of story. I'd have laughed about it over a pancake and never thought of it again. Of course, I never would have allowed my girl to tell me to grow up, either, nor would I have stared at the people in the first place.
Why are people constantly shocked when their behavior causes others to react?
Are you for real?
First of all, all people have volume control, its either whisper or don't say anything, not too hard for anyone over the age of 3.
Secondly, why should someone react to something that the OP and her dd were doing to eachother. They weren't speaking to these people, they were the ones having a private conversation.