It almost looks like the engraving was originally not filled with paint, and the previous owner filled it in.
I have done this on certain metal parts of other items made of metal that are finished to high tolerances due to the stresses they undergo, all it requires is enamel paint and some acetone to wipe off the excess.
That being said, after having seen this, I am extremely careful of watches that look even 1% "slightly off"....
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