Gaps between chrome bezel and screen

This should be covered under the warranty, so call AppleCare at (800) 694-7466, or make an appointment at an Apple Store if there is one nearby.

I have been through 7 Iphone 3G's and if that is your only issue than my advice is to leave it alone. Out of all the phones, I have still been unable to recieve a phone in perfect condition. The one I have now was out of a brand new box and still has very minor light leakage and a few pieces of dust under the screen. The dust is only noticable in direct sunlight. So just to give you a warning if its a problem that you don't notice that often then just let it be. If its a problem that bugs you then exchange it, but that doesn't mean the next phone won't have the same problem. I think all 7 phones I have received has had some sort of light leakage. Good luck!!

Most iPhone have some amount of light leak.
This may sound silly, but you can attempt to squeeze the metal bezel where the light leak occurs. Try pressing down on the screen and squeezing inwards. I had a slight light leak and this fixed my 100%. Not a fantastic fix but since these phones are plastic and just set into place, they do move around a bit.

I have exactly the same problem... Should I replace my iPhone???. Suggestions???
Thaks