Google has suddenly started seeding Android 4.3.1 Jelly Bean update and the first device to get this update is the LTE version of the Nexus 7 (2013). It is unclear what this update actually contains. Google has already patched the Android 4.3 a few times before this but this is the first time version number has been incremented. Although the size of the update (9.42 MB) kind of kills any excitement since it tells that its probably some minor bug fix.
Anyway, so far only LTE Nexus 7 has gotten this update. There are no reports of other Nexus devices or Google edition devices getting it but we’ll keep you reported of any further update.
Source: Android Police