I think it's normal for the iPhone to leak a little light because if you look at all iPhones they all have some light leaks mine has it as well on the right side as well as my parents and brother. When I went to the apple store they gave me a replacement just to make me feel better I guess but when I came home and I checked it out it also had the same thing so I think all iPhones have it so don't worry. Unless u have a major light leak where it's really bad then you should either try to go to the apple store for help (never hurts to try) or you could always buy another iPhone they cost around 100 dollars but I heard they lowered it to 50 dollars. The black iPhone 4 also has it cause my dad has it.
Just wanted to let you know your nt the only one
P.s all these phones where barley bought not long ago around 2-3 months ago
Hope I helped in some sort of way