I was running with my iPhone and I think it got a little sweaty. Afterwards I realized that a horizontal line of my screen was unresponsive to touch. Its the area where if you shake the phone it pops up the "undo" or "cancel" prompts. If that appears then I can hit undo or cancel. I have to hit the home button in most cases. Is there any way to restore a section of the screen that is dead to touch?