I recently updated my iPhone to iOS 6.1.2 and after the the update the top "power" button will not consistently lock the screen. Sometimes it needs to pressed 5 to 6 times before it will actually lock the phone.
There does not appear to be anything physically wrong with the button. It still has a nice click feel and sound to it.
I know the last update involved a bug fix for bypassing the lock the screen, so I thought others may be having this same issue.
My guess is it would be a software bug, not a hardware issue.
Other than restore the phone any suggestions?