The couple — who secretly wed in 2014 — welcomed a baby boy last fall, her rep confirmed to Page Six on Wednesday.
"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," he said. "She's just the most likable, intelligent person and adorable human being. She hasn't changed at all. She looks the same."
He continued, "We're comparing notes because my son is about a year and a half older than her young son. I'm showing her photos and videos and what to expect. We're just really enjoying each other's company."
Bledel, 34, and Kartheiser, 37, first met on the set of "Mad Men."