It is wishful thinking, but how exactly does the apple update system work? Is it a fedex/apple code built into their proprietary system? In other words, they scan the "bar code" that both reflects an Apple/Shipping method that allows the tracking info to update?
In other cases, besides Apple, with large batches, sometimes in order to expedite things or if they are in a hurry to make a flight, It is not uncommon to "skip" over a tracking update until it reaches a place where it needs to be sorted based on region.
Not sure, all speculation on our part, lol.
Though, in response to the 'skip'ping over tracking updates - it is typical that the customer receives the tracking information first - but the fedex/ups database isn't updated. Personally, I've never experienced the reverse. It doesn't really make sense since the tracking number would be generated online, and should be available when generated.
More likely, if it is a lag, it is a lag of the system in associating tracking numbers with order our viewable order status page.