The pro skateboarder shared a pic on IG Thursday of the smiling newlyweds cozied up on their big night two months ago ... in honor of his "wonderful and talented" son's birthday.
Frances -- Kurt Cobain's only daughter -- is clearly a hit with the parents ... with Tony expressing gratitude that Riley had found the "love of his life."
The proud dad also gushed he was "inspiring his younger siblings by example" by choosing a "healthy, disciplined approach to adulthood."
"We had a blast at the wedding, and we love you, Riley!" he continued -- ending with a request for Frances to show the sweet wedding snap to his son cause he wasn't on IG.
TMZ broke the story, revealing their marriage certificate showed they exchanged vows on Oct. 7 in L.A. after getting a marriage license in Sept down in San Diego ... with none other than former R.E.M. frontman Michael Stipe performing the ceremony.