IPhone 4S - after 6.1.1 update, cannot adjust ringer volume, and odd music playback behaviour

Question

This is a minor issue that'll probably end up in the hands of some apple tech, but I'm curious to see if anyone else is experiencing this.
After updating my phone to 6.1.1, I noticed that occasionally I did not hear anything when playing music through earphones. An attmept to adjust the volume simply displayed the "ringer" icon and no volume meter. When I launch a new song from stopped (not paused), there was no sound or any ability to control it. I unplugged the earphones; the play icon remained, it normally disappears indicating a pause. Plugged back in and music started coming through.
Text/Ring tones are still audible; good because I use it as an alarm clock. The phone is behaving as though it were "docked" though the music playback thing is just weird. I haven't tried playing music while it is actually docked yet.
Will try a restore tonight after work.

Answer 1

Ok, so I found this thread in another part of the forum and thought "hey maybe I should try that". I borrowed a can of compressed air from the IT guys and fired it into my phone's dock port. A few particles of who-knows-what came flying out. I've been testing it pretty thoroughly for the past hour, so far it seems to be back to normal. How a dirt particle can short the docking circuitry into thinking it's docked, I have no idea, I'm not an electronics expert...
Anyone having the same issue, go grab a can of compressed air, blow it into your phones ports (both dock and headphone jack), or try the toothbrush thing in the above link. If you use a dock regularly, keep it clean!