Next time it happens, submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. Sonos should be able to see where it is getting the ‘change volume’ command from. 

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

Ok, thanks, I’ll try this.  I appreciate the reply!

Edit: Additional question: sometimes, when traveling and on BT, I’m playing using another app, such as Apple Music (because I can’t access my playlists in Sonos app) and this happens.  What do I do in this situation? 

Not 100% sure, to be honest, at that point you’re not really using the Sonos software. I’d run the diagnostic as soon as you get back to Wi-Fi, though, hopefully enough data will be stored in the logs to be able to track. I’ve never seen a diagnostic, I imagine some data points can be stored for longer times than others, but generally we recommend 10 minutes… it certainly wouldn’t hurt to run one as soon as your able to, and call Sonos support, with the hope that they’ll be able to see the cause in the data.

My guess, based on pretty much nothing, is one of two things. Stuck buttons on your device sending the Bluetooth signal, or stuck buttons on the top of the Roam. In fact, I’d be turning off those buttons in the Sonos software, at least temporarily, as a test.