Something is seriously wrong with my iPhone screen...?

The condition of my iPhone is fine, normally. It's a 3GS and nothing has been wrong with it at all since I got it last year. But today, a few minutes ago actually, I was talking to my girlfriend on the phone and my battery was kind of low. She had to go because her mom was mad or something, nothing out of the ordinary. And then when I looked at the screen, it was zoomed in, as if I were on Safari and zoomed in too much. I can't zoom it out or anything. The most I can do is navigate it by moving my finger to the edge of the screen and it sort of scoots over in that direction. The other functions seem to be fine, but otherwise I can't do anything about it. Some lovely, caring soul, please help me.