Should I be worried about a security breach if Google Maps incorrectly shows that I drove over 650 miles from home?
In my case, the solution was to turn off location services on my Android tablet. Google Maps was using my ISP to guess my location.

Although I was in Alabama, my ISP was reporting my location as Chicago, so Google Maps assumed that since I was in Alabama one day (according to my cell) and in Chicago the next (according to my Android tablet), then I must have driven to Chicago (even though my cell was still in Alabama). Then it produced a likely route that I would have taken. Note that I seldom use my Android tablet and that the Chicago thing occurred when I first turned it on after changing ISPs.

This is the best explanation I can come up with.

So if your location service comes from your ISP rather than your cell provider, make sure that your ISP gives an accurate location for you.