Iphone 4 boot up logo has cut in middle

Hi, I just realized that when I turn on my iphone, the apple logo appears with a curved cut starting from the left... I wasnt worried until I read a post from another forum that asked the same thing. Nobody knew what was it, so the user took it to an apple store and he just received another one new, but he didnt say the problem. Should I worry about? or is it completely normal? I checked some youtube videos and it seems that the logo should appear in full white...
Macbook Pro 2.8 GHz - 500Gb - 4Gb Ram