Garmin Edge 500 question
I recently picked up a Garmin Edge 500 and noted an anomaly that doesn't seem right to me. I'm hoping some of you tech oriented riders may be familiar with the device. On two rides from my house that I have recorded so far the elevation chart shows me starting out at zero height (OK so far) then accurately shows me going down a local hill, climbing other hills and whatever, then climbing as I return home but in both cases ends showing me about 100 feet higher than I started. It should be showing me back where I was when I began or am I missing something?