An older phone used to do this to me in one particular location - it insisted that I was 100 miles away. Since the phone uses both cell tower location and a database of WiFi access points to determine location, the first question is does this happen when you are connected to WiFi? Does turning WiFi off fix the location issue? If so, then I suspect that the WiFi location database that is used to determine location (something that Google maintains) is wrong about your access point.