Music all the sudden started playing in background?

[josey44]

I had my phone on my desk and was voice chatting with a friend on an app called discord. All the sudden I heard music in the background, I thought it was my friend that had music on but decided to check for myself anyway. I was shocked to see the music playing in the background from the "play music" app. Did someone hack into my phone? I'm scared now. I downloaded antivirus and ran a full scan, it didn't find anything but I'm still worried. How could it have launched without me touching a thing. By the way it was an mp3 file that was being played. I've never had this happen before. If anyone has some info I'd really appreciated it thank you.