There's no way to know if this is legit or just for the papers.
Again, read what he actually said. All he said is that he likes his current job, and that he doesn't think he's going to be vice president. That's just the standard boilerplate non-denial that every single one of the prospective VP contenders gives. All indications are that Kaine is absolutely up for being Clinton's running mate. That's been clear ever since he gave his super early "pre-endorsement" of Clinton before she even entered the race.
If Kaine wanted to take himself out of the veepstakes for real, he could give a much stronger statement, like "I would decline any offer to take a spot on the ticket" or "I would not participate in the vetting process, since I don't want the job." He won't say anything like that, because he *does* want the job.
