Screen calibration on iPhone 4?

Hi:

My iPhone4 started acting up recently. It seems like my screens needs calibrating. When I touch the screen the "actual touch" is about 1 inch below where I put my finger!

Rebooting sometimes fixes the problem for some time but it almost does it every morning when I try to lookup my emails. When I try scrolling down an email it just clicks on the trash bin. It's driving me nuts.

What are your thoughts? Do I have a defective screen, or should I try doing a restore to factory default in iTunes?

Thanks.