Hi all, I am using the Nike+ GPS app with my 3GS on the treadmill. When I am walking on the treadmill (warming up) the mileage seems pretty bang on or not far off. However, once I start running the Nike+ GPS app starts to show my mileage as further than the treadmill does. At the end of the run it is showing my distance covered as almost 1/4 mile further than the treadmill does. Which would you assume is most accurate? I suppose while on the treadmill even though it's at a set pace you could be running faster or slower (you might be always toward the back of the treadmill or running faster and toward the front... or does that make no sense? LOL.) I'm just wondering which you would assume is correct if keeping track of your mileage. TIA.