He and his wife Sara couldn't be together for their fourth anniversary on Friday . . . because he's on the road, and she's due to give birth to their third child very soon.
But because she totally rocks, she planned a secret surprise, and the timing was perfect. He was on stage performing his new song "Boy", which was inspired by the couple's two sons, Takoda and Ryker.
As the song got going, she sent the two boys out to surprise him . . . and it SO worked. He could barely speak. He posted a clip and wrote, "What a perfect gift having my boys surprise me on stage last night. Happy anniversary my love."