metal damage question

Hi -
I have a LN #164 (Boston, MA) and in December it was mistakenly transported to Virginia/No. Carolina where it was put into some kind of storage. I don't know how it was stored (boxed, open air, etc.)
I just got the plane back (6+ months) and see what looks like small amounts of mildew in a couple/few spots on the sole (black, sort of cloudy look). I don't know if it's mildew but can't think of what else it is. I usually use parafin on plane soles so there was probably residue on it in December. I have a couple other LN's that have never left home and there's nothing like this on any of them.
I don't know what causes pitting (and am afraid to leave this crap in case it's how pitting starts) but the sole still feels glass-smooth to the touch where the black crap is. But I haven't been able to get it off (using steel wool). Any Southerners here know what it might be? And how to get it off?

net [one dot] verizon [cymbal] ballard [no spaces] mike [reverse the whole thing]

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