Alexis Bledel secretly had a baby in the fall

Alexis Bledel and husband Vincent Kartheiser sure know how to keep a secret.

The couple had a baby boy in the fall, and have somehow managed to keep it under wraps until Bledel's "Gilmore Girls" co-star, Scott Patterson, let the cat out of the bag.

"It was great to see [Alexis]. She's really blossomed as a woman and now she's a proud new mother and married and happy," Patterson told Glamour magazine. "I remember her as an 18-year-old kid, fresh out of college coming into Hollywood and being a little overwhelmed. She's just the most likable, intelligent person and adorable human being. She hasn't changed at all. She looks the same."

Bledel and the "Mad Men" actor married in 2014 -- their wedding was also "top-secret."