Check for updates should be your first step.

Do you hear it with no music?. With noise cancelation on and off?

You said "some music" can you listen to a similar track, but from a different album and see if it is still there?

You can easily remove the ear cups with a gentle pull and check for foreign objects. The cups are held in place with magnets.

Hi all - I checked without music and with plus noise cancelation on and off. No new updates either. 
 

im starting to expect it could be the recording quality - I listened to the same track through my Sonos Beam, and another pair of headphones (worse quality) and it is buzzing in that section of music as well. 
 

I will continue to keep an eye on it but hoping it is just the audio quality of the track itself. 

As a test you can call up the same track from another online service. You may be able to find another version (same master recording, but released as part of another album). 

Good idea - I tried on YouTube and same thing happened. Must be the master recording. We will see!