wow..am i the only one not to see huge problem with "not your mom" comment
agree that i feel like i'm missing something from the exchange..but op allowed that he is on the younger side...its not like the fa shoved the poster tube back in his hands...she just in a very colloquial manner was posting op that it was HIS responsibility to remember to ask for it back when he de-planed....that she wasn't going to search him out to make sure he picked it up.
maybe a touch informal, but i read her comment as trying to be human and humorous, not snide and derisive.