Apple has posted the following response to the issue:
"Most small cameras, including those in every generation of iPhone, may exhibit some form of flare at the edge of the frame when capturing an image with out-of-scene light sources. This can happen when a light source is positioned at an angle (usually just outside the field of view) so that it causes a reflection off the surfaces inside the camera module and onto the camera sensor. Moving the camera slightly to change the position at which the bright light is entering the lens, or shielding the lens with your hand, should minimize or eliminate the effect."
This is not the first complaint Apple had to address about the new iPhone. First, users complained about the quality of Apple's maps application for iOS 6, which forced the company's CEO Tim Cook to issue an apology. Then, users complained for some scratches found on the chamfered edge that surrounds their brand new smartphones, with Apple responding that such minor finishing issues are "normal" and that any aluminum product may scratch or chip with use, exposing its natural silver color.