I don't know when this came out. Checking for a software update from the phone still shows my N3 is up to date, but after seeing someone on XDA mention an update coming out today from Verizon, and nothing else from that user, I connected the phone to a PC I'd installed Kies on, and was greeted with this message.
It was the first time I'd used Kies in a couple weeks.
I don't have any issues with my phone, so I'm not going to perform this update right now.
The version number MI9 are the trailing numbers/letters in the Build number, in Settings, About phone.
The Sprint update to address audio issues was MJ4, so this update is newer.
Edit: Someone on XDA attempted this update on 11/3, got an error, and ended up having to do a factory reset.