To the OP:
It is most likely a firmware bug (MFT) that may not happen again.
It has never happened to me but I can tell you that the MFT system becomes active when the driver's door is opened (i.e. it doesn't wait for the ignition to be turned on).
You may want to pull fuse #67 and #79 to reset all modules related to the audio system.
Don't be afraid to drive your car.