The way to check for shooter error is a good stiff set of sandbags or other pistol rest or else to find a good 1911 shot and see what he can do with it or find a southpaw and see if it still shoots low and left for him (low and to the right is normal for a flinching left-handed shooter). If the sight position error turns out to be legitimate, you can shorten the front sight with a file until elevation is correct, and then apply cold blue to it. Once the elevation is correct, drift the rear sight to the right until that is corrected.
Alternately, you could send the slide to Springfield Armory with a nice tight group showing the POI error and ask them to correct the sights to match. If they are willing to do it, with indicators, they should be able to make that correction without you having the expense of sending the frame to them. However, they may not be willing to try, as they may want to see what the source of the problem is as well as to be able to test the finished result. That gives them the opportunity to replace any defective part that might be present.