So I finally got the OTA prompt, and chose accept to reboot and start the upgrade process.
It rebooted, and I got the "blue swirly Android" image for about 5 seconds, then it went to the "Droid on his back" with the red exclamation triangle image, where it sat for 30 seconds or so before rebooting back to 4.1.1
Is this because I'm rooted & unlocked ? (I rooted via Nexus Root Toolkit, and chose to retain the stock recovery console), I thought it was supposed to retain OTA capability that way ?
What do I need to do now ? (if it's unroot & relock again, I may just pass on the update, as I finally got it set back up the way I wanted again).