The AT&T variant of the Galaxy Note 3 is receiving a minor over-the-air update today according to users, following an update for the Verizon variant a few days back. According to preliminary reports, the device's responsive has improved, the Samsung keyboard's background has been changed from white to dark blue, and there's also a fix for a crash of the indexing service for some users with old microSD cards. The update will also patch previous root exploits, so if root access is important for you, it would be best to refrain from updating until an updated root method is released by the development community.
As always, the rollout will be gradual, meaning it will be a while before it trickles down to all devices. You can always do a manual check from the Settings » About phone » Software updates menu, or upgrade by downloading the firmware once it becomes available in our firmware section.