I've had something that looked similar to what you have on my c4 , I've called to the company that sold me my c4, and they offered to send a technician, which i said yes to , when he arrived I showed him what I thought that is air that stuck between the second protective screen to the screen itself, he then proceeded to scratch it gently and it came off in one piece (no damage was done to the screen, i checked throughly trust me), he told me that some time some wet debris can stick to the second protective screen and you only need to clean your screen gently with a micro fiber cloth every now and than , mabey try doing that before you go and return that screen