What's the deal with the packaging on Grease? I saw it at Wal-Mart the other night and it seemed to be a single-disk digipak from what I could tell. But then I saw it at Costco yesterday and it seemed to be a keep case. Has anyone bought theirs from Costco or seen it at Costco to confirm this? Are there different packages (aside from the different artwork for the OAR/MAR versions)?