It has absolutely nothing to do with Pandora. I have never used--even installed--Pandora in my entire life lol.
I think what we need to highlight here is the fact that when you put your finger on the volume slider to slide the volume up or down--even if you do it super slowly and carefully and then let your finger go--the volume slider slides COMPLETELY to the highest level volume, regardless of where you just slid it to. I believe information like this, when in the right hands, (such as a coder's/developer's hands, or Google's hands, or LG's hands), could help them track down the issue.
Edited to add: Of course, I mean doing this while the headset (in my case and most others' cases, LG Tone+) is connected to the device through Bluetooth.