its god to get into the habit of making your scans perfectly square. It's import for them if the scan is ever going to be placed into a square box. Most scanner software has a crop area that's settable or lockable. This one shows as 477x473. Close...but not exact. You will loose some sharpness at this level if going into a box (like with any of the online chipguides, or even Collectors Assistant database ).
I know its a test, but thought I'd give some input. BTW, scan looks nice and sharp.