I was kind of surprised that PJ didn't get the call ahead of Sampson. This would have preserved Sampson's redshirt year, giving him time to get more comfortable in the offense and time to develop more upper body strength in the weight room.
Also, all the reviews from practice that I have heard is that PJ looked impressive, even as far back as last year.
Maybe that kickoff return finally gave him a chance to show his stuff and earn some more playing time.