An almost two months delay is too long. Of course I want them to get it right, but this is a big company and they should have their process in order. They've built the case before, only the specs have changed. A couple of tweaks to a computer model and this should have been manufacturing.
My guess is that something went wrong, either with design or manufacturing.
And I don't believe Apples secrecy is a factor here. At least 30 other companies have their product to market and everyone came out of the gate together. I don't mind waiting for this case. I just feel the wait was too long.
It's not just changing the computer model. They also have to get the cases approved for all of the standards that they advertise. If they change the case to accommodate the different specifications of the new phone, it's possible that it will no longer meet the standards, and they'll have to keep going back to refine the case.