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 — its going to be hard to find. Confirming recent speculation on todays earnings call, Cook said that its not clear if well have enough stock of the Retina iPad mini when it launches. He also said that while he expects Apples opening weekend for the full-sized iPad Air to be strong, its not clear that everyone who wants one will be able to find one. …