[mieses]

I've had mine since May. Probably the rubber coating can be destroyed if you clean it too aggressively. Don't rub it with a cloth or an anti-static wipe. That will just cause small fibers to stick to the tacky rubber.

How to clean it: http://itecsoftware.com/how-to-clean-your-nexus-wireless-cha...

In my case the charger sometimes sticks to the phone when I pick it up.