Funny story here. AT&T just updated their Moto X (1st gen) support page to show that the device is getting an update to Android 5.1 starting today. While that would be fine and all, we have to point out that it appears they updated the wrong page. The Moto X (2nd gen) is actually the phone getting the update. Why would we say that? Well, because the “Verifying the Update” section on the support page details a phone under codename “victara,” which is the 2nd generation Moto X. The 1st generation Moto X actually carries the codename “ghost.”
So yeah, even though you will probably see others report that the Moto X (1st gen) on AT&T is getting updated to Android 5.1, it’s not. The 2nd generation version, which is currently going through a soak test, is the phone getting the update. Again, XT1097 is getting updated to Android 5.1, not XT1058.
The new software build is 23.16.2 and weighs in at around 507MB in size. AT&T says that you will need a WiFi connection in order to grab it.
Be on the lookout through Settings>About phone>System updates.