Ive had my plus for about 4 days now, I was applying screen protector and i noticed when it is on a flat surface it wobbles slightly. It will not lay flat. Ive tried other surfaces and same result. I placed my 5s on the same surfaces and it sits solid. If you hold the phone vertical, you can slightly see it bent. Ive had the Apple Leather case on it since Ive owned the phone. How should I respond to this? Thank you.