How to resume normal iPhone volume after notification causes volume to get stuck in lower volume mode? iPhone 4, iOS 5.0.1

Strange problem I've had for a few months.  Sometimes when a notification causes the iPhone to temporarily lower the volume, the volume gets "stuck in quiet mode" and doesn't resume full volume.  As a result, music playback is approximately 25% quieter than normal.  Sometimes getting a subsequent notification is enough to kick back to full volume.

This is very annoying because I never know when the phone is going to ramp up the volume suddenly (if I get a text message for instance).

What could I do on the phone that would force it to kick back to full volume?  Something better than asking a friend to text me, or setting a 1 minute alarm, etc.
Yes, I too have had this problem many times. (I have been told it is a known bug in iOS having to do with playing MP3 files that are shorter than two second.) The easiest way to get your phone back to normal volume is to pause the music (or audio/video, as the case may be) and then resume it. The volume should be back to normal after that.