We need photos to tell for are it's an incorrect front sight. Colt did supply Pythons with a red insert front sight before transitioning to an orange insert. I'm not sure but I believe Colt was still using all black front sights but that's roughly around the time they were changing.
Did you try and let someone else shoot the Python and see if it was shooting low for them as well? Are you shooting reloads or factory loads? Many reloaders load on the light side for liability reasons. What bullet weight are you shooting? Heavier bullets will hit higher. Make sure it's not the ammunition or your shooting technique before condemning the sights.