I plug mine in at night, let it charge while I'm asleep and it must be fully charged and still plugged in for several hours, so I don't think that that is the issue (at least not in my case).
I only have used the included cable, so I don't think that it can be definitely associated with a non-Samsung micro-USB cable either.
The only thing I did differently the 1 day that this occurred on (and I have done the same thing since, and it has not happened again, however), is that I used an off brand car charger (to USB), and used the standard cable.
I'm clearly limited to an n=1 here, but that has been my experience.