Mine did this crap just yesterday.
I pulled the usb charger out of the phone and woop, it came off.

This issue better be in the warrenty, especially when you think about how you have to freaking re-charge the phone just about everyday ( which imo is actualy really annoying)
So i'm heading over to the store i bought it from to send it to get it repaird.
I was told if they cant repair it, or if it keeps happening, i'd get my money back.