You are correct, but I did not notice it before. It appears that there is a thin buildup of braze material on the front sight, filed into a partridge sight shape. But there appears to be blue on the sides of the front blade.
Since the front sight was built up and not filed down, I assume it would be easy for a good smith to restore the sight blade to its original configuration. It looks fine the way it is though. Nice pair of guns you have there.