that will polish out with a bit of effort
with regard to stainless and damage if that was the case the inner plastic sleeve between shaft and prop is designed to shear and spin free, forgive the lack of names for the parts but Im reliably in formed from steel developments to prevent that risk to drives on impact* - instant stop etc. If you havent got this plastic insert then something is amiss

and you are at risk.
* major impact i.e. rocks not legs and arms etc.