Just out of curiousity, what does the term "unexpected supply delay" mean (Of course, this is from an Apple Store automated e-mail) specifically?

It couldn't possibly mean that they're out of stock, as my 3G 10GB iPod has apparently been ready to ship since the 13th (And is according to one rep "sitting at the dock" without mentioning what city or location), according to two customer service reps. They also promised tracking numbers on two different days, but I never got 'em. So I'm guessing it has something to do with the "supply delay".

Thanks for any help.