Possibly, but on an airline with cramped seating, who could she flash? She didn't have any luggage to stow, so she wasn't going to need to reach up and/or bend over.
Either someone whined to Keith and played a PC card, and/or Keith is a pervert.
That handbag had to be stowed, and it’s my guess that old Keith got a “view at the top” when she bent down to put it under her seat or the seat in front of her.
Heck, if they have no dress code and she was going to see her “doctor” why not just board with the paper gown?