Guys, there have already been threads on this.
It's a bug, I confirmed by turning on wifi and watching a few youtube videos, my counter climbed by a few MB. I have called Apple and let them know, and they said I was the first call about it.
You all need to call them because the more input they have, the quicker they will prioritize a fix. Always call to report bugs, it helps them and us.
Mine even started showing "tethered data usage" and I don't have a mobile hotspot activated, plus wifi and bluetooth were both off. I called Verizon and they had no activity, yet the phone started counting all data as tethered. When I hung up from Apple, the tethered data had magically reset to zero....then went away after restarting the phone.
Don't trust the usage meter, it's a bug in iOS6.
And above all...call Apple, all of you!!!