Razzing my son

Is it wrong to tell a former Marine you're going to get him the new Tinkerbell movie for his 37th birthday?
It's been a long time since Danny and I have just been silly together. His problems in his life and Mike's death have kept us pretty serious.
But the other night, I just messaged him on Facebook and told him that's what I'm going to do.
He called immediately and asked where that came from. I told him I was watching one of my socialist TV shows and there was a commercial on for the new movie, which is coming out om DVD the day before his birthday.
It was good to just laugh with him like we did in 2004, when I put a Red Sox screensaver on his computer after my team won the World Series (he's a Yankees fan). He told me he had put a Bush/Cheney bumper sticker on my car and I told him I would put a Kerry/Edwards bumper sticker on his truck if that was true.
"You don't have one," he said, and then started chanting "Mom's votin' for Bu-ush."
I pulled a bumper sticker out of my briefcase and we just laughed.
He took Mike's death hard -- we all did. But he's finally coming out of his grief and starting to find some peace.
I am getting him that movie, though.