Anyone who saw Mad Men‘s season 4 finale knows that Peggy was not happy with Don’s big announcement.

Now, the actress who plays the intelligent character is speaking out about Peggy’s reaction and what may be to come in season 5!

Elizabeth Moss spoke to The Envelope:

Granted, it has been a while, but do you remember Peggy Olson’s jaw dropping when Don Draper sprung his engagement news on the folks at Sterling Cooper Draper Pryce in the Season 4 finale of “Mad Men”?

Turns out that reaction didn’t involve much acting on the part of Elisabeth Moss, the Emmy-nominated actress who so memorably brings Olson to life.

“Oh, yes, reading that script, that moment came as a complete surprise,” Moss says. “And I think Peggy’s reaction is there as a stand-in for the audience too. ‘You’re what?’”

Some dedicated “Mad Men” bloggers have suggested that Peggy’s reaction betrays a hint of jealousy and concern that she might lose her place as Don’s confidante, particularly after their memorable (albeit platonic) night together in the episode “The Suitcase.”

“I think that’s a dangerous thing to say,” Moss says. “People are quick to think that Don and Peggy are an item that way. There are many forms of jealousy. [Don’s fiancee] Megan’s a beautiful woman. I don’t think Peggy wants to be the one engaged to Don. It’s just sort of a natural female jealousy.”

But will Don and Megan still be engaged — or perhaps married — when “Mad Men” returns for its fifth season in March?

Moss isn’t spilling the beans. But she does offer a tantalizing clue that tracks back to Peggy’s initial shock.

“I think there’s probably more to be revealed as to why she reacts that way,” Moss says, smiling. “But … um … that’s probably all I should say on the subject.”

We can imagine seeing Peggy in a shocked state of mind at least in the first episode or two of season 5.