Nope. I don't sit on my phone. Front or back. So my phones are bendfree. And it doesn't bend by itself either.

Many people put their phone on their back pocket, which is actually very non-recommended. As long as you don't place your phone under a long-term stressing force, you shouldn't have a problem.

Bend i never face before but i face before warp on both Nexus 5 and Nexus 6. When it's new, put them on a flat surface table face down they lie properly flat. After a few months use, the phone will warp even i use it with case and then i put it on a flat surface table again, i notice they wobble like a ship from side to side. Another of my discovery is Nexus 5's sides will even gets hairline cracks by itself near the sim tray, volume rocker, and audio jack. Searched on Google and found out that i'm not the only one. Mind you i didn't wear tight jeans or put the phone in my back pocket, i handle my phone very carefully and even better than a girl. LG tsk tsk tsk...every manufacturers have their shortcomings.

On Spore hardwarezone no bending problems reported. Several users reported varying display problems from yellowish to pinkish. I saw the pinkish display n it was indeed horrible. Those affected users are waiting for HW Spore response as initial indications are no replacement of phone n probably replacing display only. Nothing can be done yet as no parts available
My unit has been perfect with no bad build quality or display issues.