I don't think I'd even want to get the box autographed. I respect him for getting to the professional level as a BMX biker, but since it's not a sport I really follow closely I'd just feel fake asking for a signature. The only times I've ever gotten stuff signed was from producers that were djing in town, and I got my Se7en dvd autographed by David Fincher after he gave a guest lecture in college.
The only time I was salty about missing an autograph was when everyone else I was with got the custom Daft Punk jackets we had made signed by the guys at the after party in Brooklyn back in 2007. I missed my chance by a few minutes because I was waiting for stragglers that went back to the hotel before coming to the party and I had the tickets.