Partial Source: The Wrestling Observer
It was noted by many among the wrestling media that current WWE Champion Dwayne "The Rock" Johnson made no mention of being champion, WWE or WrestleMania 29 during his appearance on "The Tonight Show" with Jay Leno this past week.
According to sources, this likely means the team representing the new "G.I. Joe: Retaliation" film set up the appearance and he was told to only plug the film.
A majority of the time when bookings like this take place on talk shows with celebrities, what will be discussed and plugged is decided far ahead of time by the people doing the booking. It appears as if WWE had no part in this booking.