Apple may have put in a bigger manufacturing order under the assumption that the iPhone 5 was going to be hard to make. Turns out it's not that hard to make, so Apple can cut its order.
While that's a relatively benign reason to cut orders, some analysts still think it's a bad sign Apple cut its orders at all. They think, if demand was great, then it would just keep the machines cranking in overdrive, regardless.
And while, that might make some sense, we can think of another reason Apple could start cutting back on its orders of iPhone 5s.
There have been multiple reports of Apple releasing an iPhone 5S, the next iPhone, in June. If Apple really does put out a new iPhone in six months, then it makes sense to cool the manufacturing facilities in the first quarter of the year. It wouldn't want to build a massive inventory of iPhone 5s, if it's only going to replace it a quarter later.