Really?

I picked the kids up from school today and on our way out the door I said "Say goodnight, Gillian." Gillian turns and says "Goodnight Gillian!"

I have a bad tendency of saying "really?" when I get frustrated. Tonight on our way home from school the car in front of me hesitated a few seconds at the green light. I honked my horn in an attempt to move them along. From the backseat I heard Gillian say "Really?!?!"