I was concerned we had a (white) mold issue until I researched a little and determined it's just crystalline efflorescence.
There's maybe a couple little tiny spots developing what may be black mold, but I'll hit it with some bleach water and a brush and knock it down.
Everything is mostly dried up now, I just need to pull up the carpet remnant. Good excuse to get rid of the ugly 80's dark green mid-pile thing anyway. The only downside is I installed 3 telco racks full of stereo gear on top of it. Since it's coming out in pieces anyway, no big deal really.