I had a similar experience when my home button went bad. I had already been through several replacement iPhone 4s for various issues. I had finally gotten one I was happy with, and a few months later, the home button started acting wonky. It would register double clicks as single clicks, single clicks as double clicks. Sometimes I would click once and nothing would happen, and then I'd click again and it would open the multi tasking bar as if it saved the first click for later. After completely restoring to factory settings and reinstalling all my apps from scratch, I took it into the Apple store.
The genius would not help me because I couldn't recreate it at the store. He said all home buttons do this and that it's "all about timing". He also took the back off of my phone and blew dust out of the home button, and appeared to have slipped with the screwdriver in the process because there was a nice scratch on my phone's antenna band when all was said and done.
I walked out unsatisfied, and that afternoon, the home button was back to its same bad behavior. I made another appointment and took it back in. Of course, I was not able to recreate the problem at the store, and I also ended up getting the same genius. His body language said it all--he leaned back against the back counter behind the genius bar and more or less said, he wouldn't look at it again and would not replace the phone even if he could get it to happen at the store. He maintained his belief that the issues I was describing happen to ALL iPhones and iPods.
I was furious. When I got home, I called Apple Care and complained to a manager. She sent me a brand new in the box iPhone 4--still shrink wrapped and everything because she decided I had too many problems with the refurb units I was given in the past. That's the phone I have to this day.
