Apple really needs to get better coders for the calendar portions of its app. The company has a long history of daylight saving time FUBARs, and on Jan. 1, 2013, a slightly different, but calendar-related issue popped up.
Some iOS 6 users who use Apple's scheduled "Do Not Disturb" feature have found that their iPhone, iPad or iPod touch never seems to exit the scheduled window. The "Do Not Disturb" setting is supposed to completely silence an iOS device, including calls, alerts, and notifications, while it's locked and within the scheduled timeframe. With this bug, the device never begins "disturbing" iOS 6 users again.
Manually changing the "Do Not Disturb" function to off and then on again seems to fix the problem for some people. Others see the problem fixed when they reboot their device.
At any rate, it seems Apple's developers have a big problem when it comes to transitions, such as the aforementioned Daylight Saving Time, or this transition from 2012 to 2013, since it happened sometime in the crossover period.
It's hard to imagine why Apple can't get this fixed once and for all, but at least they didn't omit a complete month, as Google did with Android 4.2.