It may be sold out everywhere but Apple usually keeps a set number aside for replacements. For dead on arrivals and so forth
That`s what happened to me.
I got out and didn`t notice until about 30 minutes later that there was NASTY terrible yellow bleeding (not just the whiteish light bleed) and a wretched red pixel issue.
Went back in and the guy first said `Dude, I`m sorry, we`re completely out of these, I`m not sure what to tell you...`
I nearly had a heart attack as I`d have needed to wait at LEAST 1 month + to get a replacement as I was in Canada, the release wasn`t for another 14 days.
And driving back down to the Apple store was a no-go, it`s 2 hours....
Luckily the guy checked, went back and came out with a replacement, my heart soared. This one was much better, minor bleed but I`m used to and expect it, whitish - not smoker yellow and no pixel issues.