Default [Q] Google Play Music no album artwork on lock screen

Hey guys, just got a Moto X and love it. But yesterday night when I was playing music, I unlocked the phone and the album artwork is missing..
The pause and skip buttons appear and work just fine its just the album artwork is gone along with the song title and everything, only shows my wallpaper with the screen controls.

Is there any reason as to why this happened/a fix?

Thanks for any help!