Yep. Then again, he was 23 at the time. Since then he's won almost everything with them and now they're going to have to rebuild. Maybe he wants to pursue other venues. Earn more, challenge himself in a new league.
Either way I doubt Juve will even contemplate selling him unless he's pushing for a move. He's pretty much the perfect Allegri player. This is the manager who almost killed Pirlo's career at Milan because he thought Antonio Nocerino was a more worthwhile footballer. He adores physical midfielders, and he's got possibly the best one in Vidal.