When I bought some shirts and stuff off the site, I called the order in. They checked stock on the items as I listed them, and I was surprised when they said "Yep, we have 6 left of those. Ok, 4 of those. 12 of those, only 2 left now of that one."
So it's not too surprising. I wonder if the website gets updated real time with stock, or if they sometimes sell out before it gets unlisted.
Mike