Transparent screen not quite flush?

The iPhone 4S transparent back doesn't sit quite flush w/ Verizon iPhone 4S. It appears to be off by a fraction of a millimeter, enough so that the flash isn't centered with the hole.

I would need calipers to measure the minute distance. The best indication is that the camera and flash holes aren't perfectly dead-centered over the elements.

I have removed/reattempted several times, verified that there aren't any manufacturing boogers or burrs on the catch-ears.