It has been claimed that several early adopters are noticing that their iPhone 5S units are bending backwards due to an unknown reason, though reports of this happening are isolated at best.
It warrants mentioning here that a similar issue was reported last year when Apple released the iPhone 5. Some early adopters found that their iPhone 5 units were a little bent straight out of the box, while some noticed the issue a few days after they had started using their units. Still the issues reported back then weren’t widespread and the units certainly didn’t bend as much as the iPhone 5S unit seen in the picture.
Apple hasn’t commented on reports of iPhone 5S bending backwards and it is not known for sure exactly what is causing these reported issues. Apparently only the early adopters in China have seen their iPhone 5S units bend, because similar reports haven’t come in as yet from any of the other markets in which the iPhone 5S is available. The issue seems isolated at best, and there’s also the possibility that these images might be fake or manipulated in some way, so its best not to assume that there’s probably an inherent structural flaw in the iPhone 5S design.
One can only wait and see if other customers report similar issues, if not, its likely that this might be an issue with a particular batch of units, keeping in mind the possibility that all of this might just be fabricated to begin with.