So it's in typical Apple style but they have issued a piece of supporting information in reference to the DND Glitch. Which is pretty similar to the advice that was issued earlier by this blog.
As it states :-
iOS 6: Do Not Disturb mode stays on after scheduled time
iPad, iPhone, iPod touch
After January 1st, 2013, Do Not Disturb mode stays on past its scheduled end time.
Do Not Disturb scheduling feature will resume normal functionality after January 7, 2013. Before this date, you should manually turn the Do Not Disturb feature on or off.
To turn off the scheduling feature, tap Settings > Notifications > Do Not Disturb and switch Scheduled to Off.
This document will be updated as more information becomes available.
Because of this being fixed I believe Apple will now build in a fix into iOS 6.03 which is currently on Beta 4.
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