Alright! We all know that it isn't easy to come up with latest software update all the time. OEM like HTC, Sony rarely release update to their phones but there are OEMs prompt on updating their device. Motorola joins the league of "OEM with quick software update" as they have cared for customers.
Moto X 2013 Android 5.1 OTA Update
What you are seeing is the newest Motorola, once owned by Google but now a property of Lenovo. That hasn't stopped them from delivering the latest software update to their new Moto line of phones. Moto X 2013 was update to Android 5.0 Lollipop and now this phone gets 5.1 Lollipop update in United States, Canada and Brazil. Now this is official news as David Schuster (Google+) the Senior Software developer at Motorola Mobility on G+ posted this official news.
This update is costing 222.21 MB of space and you should atleast have 300-400 MB space free that on your phone's internal storage.
Via - Motorola Global