AFAIK, its called a Light Bleed. And that comes under 'defective'. If HTC doesn't replace it, you can always write to higher authorities about it, asking for help. But first try to get the local stores to acknowledge this issue. Don't go to one, visit at least 3. Even if one of them agrees, just pressure him to take it back and give u a new phone. Otherwise, tell them you have no choice but to write to higher authorities. HTC is NOT in the position to let any such case to come out in the open. All the best. If you need help, PM me. I can help you further.