It was December 2012, and Danes and her husband decided to do a little shopping just hours before she was scheduled to have her labor induced.
"So people kept coming up to us in the store, saying, 'I'm really excited for tonight!'" she recalled to host Kimmel, adding that she thought, "How do they know? Who leaked that?"
Then she remembered something else was just hours away — the season-two finale of her Showtime hit, "Homeland," which was what her fans really meant.
But what she (and her fans) didn't know was that she was already in labor, a point that became evident when Danes made it the hospital and the nurses told her there was no need for her to be induced.
"It started to really come on throughout the night," she said. "I couldn't get to sleep because I was in, I guess, acute pain. But I wasn't clocking any of this."
So, with Dancy sleeping in the next room, what was a laboring lady in denial supposed to do to kill some time?
"Then it occurred to me, 'Oh, yeah, the finale aired! I wonder what people thought,'" she mused.
And, boy, did she find out.
"You know, at 3 in the morning or something, when you're looking for feedback, what you mean is, 'Who hates me and how much?'" she laughed. "So it didn't take long for me to find the worst possible reviews available on the internet."
That's when it occurred to her: She was in labor and reading scathing criticism at the same time.
"I don't think it gets more masochistic than that," she said.
She decided to then put down her phone, forget about the feedback and patiently wait to welcome son Cyrus to the world.
While, in retrospect, she knows reading those bad reviews was a mistake, she also knows it's one she won't repeat when she goes into labor later this summer — and not necessarily because she's learned her lesson.
It's because this year's "Homeland" has already aired.
"So we're good," she said.