By Meghan Overdeep
Updated Dec 01, 2015 @ 12:30 pm
Credit: Shawn Ehlers/WireImage

Even though she's all grown up and out of the house, John Stamos still has a soft spot for his on-screen niece. The news that Mary-Kate Olsen—one half of the identical twin duo who played Michelle Tanner on Full House—married her longtime boyfriend Olivier Sarkozy, had him feeling understandably nostalgic.

"'In the blink of an eye.' Congrats MK. X," Stamos captioned a black-and-white photo of himself and the Olsen twins as toddlers on Instagram.

The Grandfathered star played Uncle Jesse on the wildly successful ABC sitcom Full House, which ran for eight seasons between 1987 and 1995, launching both his career and the careers of his costars, beloved child actors Mary-Kate and Ashley Olsen.

In April, Stamos confirmed that the series would be returning to television, although the Olsen twins reportedly passed on rejoining their former castmates for the 13-episode reboot, Fuller House.