Got iPhone 4S on Saturday. I already had it replaced on Tuesday because of faulty speaker (echo issue). Now when I was turning it for the first time (home) I noticed dead pixel on the very top and to the right. Its only visible on black background. Its very visible when restarting. Now I don't really want to replace it because I really have to stare at that spot for long time to "find" it. It doesn't affect functionality of the phone. My question is should I have it replaced? Or I can leave it the way it is? I never had any phone or other device with dead pixels. So is it mark of a faulty LCD?