Location detection by your IP address is only about 85% accurate. In the future I'll allow location refinement, right now I wouldn't worry about it. Your results will be calculated the same either way, you'll just be compared to people in your adjacent city.
On mobile this issue is much more noticeable. Where sometimes you can be assigned an IP in one city... and travel with that same IP for a while. GPS location refinement will fix those issues but I have a lot on my plate and have no ETA on that.
Mine says "Monument CO" -- my address is actually in Colorado Springs... but really I'm much closer to Monument. So it's wrong but not totally. Personally I'd rather be compared to people in Monument because it's closer to where I really am.
While I'm thinking about it... I'm going to manually update my IP tables database. It may correct the detection for you... it may not. But don't worry too much about it, it's generally accurate and doesn't affect the outcome of your speed test.