If you were hoping to get your hands on the iPad mini with Retina display at launch, Apple CEO Tim Cook has some bad news — it's going to be hard to find. Confirming recent speculation on today's earnings call, Cook said that "it's not clear if we'll have enough" stock of the Retina iPad mini when it launches. He also said that while he expects Apple's opening weekend for the full-sized iPad Air to be strong, "it's not clear that everyone who wants one will be able to find one." Despite some potential supply concerns, Cook says that "it's going to be an iPad Christmas" and called the Air "the best iPad we've ever done." Reading between the lines, it looks like Apple expects its currently-flat iPad sales to be a thing of the past next quarter.