I have silently concurred with you for a while, NP.
I have watched Peggy's long, slow, sad spiral down into MoDo-style bitterness since after 9-11.
I also note S-9's thought: is she bowing to peer pressure? The party invitations seem to be a motivating factor in a lot of people's minds, it seems...
I think that Peggy is VERY angry and bitter about no longer being an "insider" in the White House.