Nope, being under-endowed in the rear is not something I've ever been accused of, not even by the most delusional. I was thinking it was more an age dig, since I correctly assumed what a bustle was.
wink wink honk honk
sez you . . . besides I never said that I'm one of those who thinks you're underendowed in the rear . . . i thought your derriere was fine.