After one month mine got the clicking sound issue too, on the lower right bottom and upper left. For the former after pushing thus clicking it and wait for a few minutes, it'll become "loose" again and then I could push and click once more. For the latter it's consistently making a popping sound if I pinch that corner and then releasse. From the outside the phone otherwise looks perfect, no sticking out of the glass for example, but it's weird nonetheless.
My home button on the otherhand has always been loose for about 3 weeks. The slightest pressure and then release it will make a click sound. And if I pull in the lighting adapter and slightly make it "push" the inside of the home button then the noise goes away. Apparently there's something loose in the home button. 🙁