I don't know, I plugged mine in the night before last, like I always do, woke up the next morning to about 25% charge. It was plugged in, but was not charging. I fidgeted with the plug, bent it, angled it, played around with it to see if I could get it to start charging. It only started to charge after folding the power cord underneath, forcing the micro usb plug to seat at a slight angle.
I thought it might be the power supply cord and/or power supply, so I tried it with the one in my car, and the same thing happened.
Tried it again with the charger at my office, same thing.
Put it under the microscope to see if the male micro usb edge fingers were damaged, but they are not, just alot of dust and lint in the housing, so I pulled it all out, tried charging again, same thing as before.
Gonna take it to Sprint to see if I can get a replacement.
Also, I get the random reboots also.
Not sure if I want to keep this phone, went overseas this past spring, didn't buy a handy when I got there, just used the Google Voice and Sipdroid, and while it was free, boy was it a hassle to try finding a hotspot just to make a call. Won't get a stateside-only cell phone ever again.