My phone is about a week old. I noticed the camera lens is a little loose. This video is not mine but it is doing exactly what this guys phone is doing and he got a replacement from AT&T
I Had black spots appear in my pictures so I took it to a sprint store and they replaced the camera. Not the phone. And it cost me $50 because I don't have insurance on it
the camera lens shouldnt be loose. one thing you can attempt if youre wanting to is to put slight pressure on it and see if it clicks back into place..SLIGHT pressure..do NOT push on this thing like youre trying to perform CPR..if it DOES snap back into place test that mofo out like no tomorrow..if everything works youre good to go..if it still has some issues take it in.
then go back in and locate their S4 floor model..check out the lens..if it moves then there is your answer..if it DOESNT..then THERE is your answer lol..it shouldnt move..it should be fully sealed in place..