OP ... check on your phone to be sure none of the settings for the Music app for playback were somehow altered. If you Volume Limit is on and set too low the AirPods can be affected too. Mess around with Sound Check too.
gigaguy, I thought you were joking but I just reversed and put the AirPods in upside down...the sound does change. I'm guessing the opening is angling more directly down your ear canal when placed this way.
Not sure I agree they look better this way...buy hey, they are not winning any style competitions anyway.