"Product transitions are never simple," Cook answered. "And remember, we have to call [manufacturing numbers] many many weeks in advance."

Marshall bought that explanation. "I do think it was the transition," he said. "The iPad 2 is 33% lighter and 15% thinner. It's not that easy to build them."

Gottheil also didn't believe Apple made a error in forecasting. "Anytime there are people still queued up for a new product, I can't see how you screwed up," Gottheil said.

Also important to remember, said Gottheil, is that while Apple has several years of experience in predicting iPhone sales -- and matching that with production -- it has only one year with the iPad.

"I'd argue that Apple did customers a favor by telling them, 'Oh, by the way there's a hot new one out soon,'" Gottheil said, talking about Apple's February announcement that it would start shipping the iPad 2 the following month.