I had the problem on my 2012. I discovered that I had mounted my cell phone too close to the volume control switch. I moved my phone to the right handlebar grip area and that solved the problem. A cell phone "pings" towers to let them know the phone is in the area. These ping signals can apparently be interpreted as volume up signals sent from the thumb switch on the bike.
Darkside Rider # 1238
Patron Member of the NRA
Life Member of the GOA
Proud Member of the 3%
Sandy Hook was STAGED. I will pay $25,000.00 to the first person who can PROVE otherwise.