Iphone users can tell you how important the home button on the phone is. Time and again it goes out of calibration (it did it twice for me in last year and half). In my case It got so bad that some times I had to click multiple times before the click got recognized and the ,more frustrating the behavior was random for it sometimes would treat multiple clicks as multiple clicks itself. I would have taken it to the Apple’s Genius bar but the phone was out of warranty.
While looking for solution on the web, I came across a simple one. The solution was to turn off the phone and stick a vacuum cleaner or an air blower to the place where stick the charger. Since I had nothing to lose, I decided to give it a shot. Instead of air blower, I used the vacuum cleaner and vola it fixed the problem.
I have repeated this step twice so far and have gotten good results both times, so give it a shot before tearing apart the phone or driving up to the genius bar.
ps: There is one more software solution, I came across. I haven’t tried to see if this works, but you could try.