ok, so i am a idiot.
i checked my usb adapter in my Z which has both 1A and 2.1A charge rates.
my hero2 was plugged into the 1A..thus not enough juice to charge while recording.
wtf..
not sure when i accidentally switched it, but now i have it plugged into the correct
charge rage.
and i can use an icy cold diet pepsi in hand...