volume stuck on high or low

I have experienced on my 3gs that my volume gets stuck on either the highest setting or lowest setting like its button is continually being pushed and will not get off that setting. I do have an iskin case but it still will be stuck even when I take off the case. I have to shut down the phone to get the volume icon to turn off and the volume controls to not be stuck. This has happened three times since having the phone. Its most frustrating when I am listening to it in the car and cannot turn it off and back on when driving. Has anyone else experienced this and does anyone know why its happening? Like I said before I thought it was because of my case but it continues to stick even after I take the case off. I know apple has the beta 3.1 out and it will contain lots of fixes that people have been experiencing but I have not seen a problem that looks like mine in this discussion thread so I am not sure Apple knows about this or that it is wide spread like the other problems to get a bug fix. This problem is easily fixed and only an annoyance because I have to restart the phone to get it to stop.