iphone 4 volume indicator problem

Hi guys,
I am facing a weird problem with my iPhone 4.
It happens to me frequently and is killing me. The problem is that the ringer indicator keeps popping up even though the volume control buttons are not pressed.
When it happens, I can only decrease the volume and the (+) button does not function at all. I tried restoring and updating to 4.0.1 several times, but once I install my apps it just happens after a while of using the iPhone. I tried installing different apps everytime, yet it happens.
Has anyone experienced this issue with iPhone 4?

http://www.youtube.com/watch?v=miChMRU3voE

 

Yes sometime it does, sometimes it just stays where it is.
Mostly the case immediately appears after unlocking to home screen.