Apparently, a new update to the Nexus 4, 7 and 10 is so good it actually repairs the space-time continuum. For a little while now, the month of December has been missing in the Contacts app on Android 4.2 equipped devices. This along with a few other bugs, like wonky Bluetooth, suggest that Google didn't leave the cake in the oven quite long enough. Luckily, they figured out just how much longer to prepare it, and a new Android 4.2.1 rollout is spreading out to the newest Nexus devices. This new update fixes the majority of these issues, including restoring December.
Whew! At least now Google won't have to send Andy Rubin through a time-portal to fix things!
Source: PhoneArena