Worst case scenario, he separated it. I doubt it since he went back out there and gave it a go again, but that would be the worst case. In that event, he more than likely would still be ready for Week 1. As someone that has had some shoulder issues (stemming from football), it sounds like he may have popped it out of place a little bit. Probably a partial dislocation that they put back into place. His range of motion probably wasn't what it should be and they felt it best to call it quits and save him from a fully padded practice. But, again, that's just a guess based on my own personal past experience.