Problems tracking iphone usage

Ive been trying to use this to keep track of my data while using my iPhone tethered via USB for my connection. It keeps jumping up suddenly to 4.01GB data in and 4.01GB data out, for 8GB total. Somethings wrong. I know thats not "wi-fi" but it says its tracking it, so either it shouldnt show up or it should track it accurately.

jtbayly about Bandwidth+