3rd generation iPod touch sleep/wake button

I have a 64 GB 3rd Generation iPod Touch running iOS 5.1.1

I have recently noticed that there appears to be a problem with the sleep/wake button.

I listen to music on my iPod with the screen off (not glowing - iPod is on and music is playing but nothing is being displayed on the screen), and my iPod randomly lights up as if I had pressed the sleep/wake button.

This happens when I do not press the button and the screen turns on, then off, on, off, and so on repeatedly like the sleep/wake button was being pressed. I also quite frequently notice that the power off swipe function appears - which occurs when the sleep/wake button is pressed and held for a few seconds - during these episodes.

However, when I actually press the sleep/wake button, the iPod does what it's supposed to do - the screen either turns on when it's off or turns off when it's on. I have also noticed that simply by not pressing the sleep/wake button, the screen on/off episode ends.

What is going on here? Is this something that can be fixed? I have reset the iPod by pressing and holding the sleep/wake and home buttons at the same time, but this did not fix the problem.

What can I do to fix this?