Hey T. Harper thanks for responding. I don't think it's spider mites. There's nothing crawly as far as I can tell, and sifting through the soil I can't find anything. The stuff at the base (the older stuff) is turning brown and just kind of gooshes and smears when I touch it. The plants still seem healthy though. I'm curious what it might be. I put them outside for now, so maybe something will eat it or whatever's causing it. I have plenty of stock and I don't feel like washing/microwaving, so I'm just taking more cuttings. I'll definitely nuke the soil next time though. I always mean to since it sits in the garage for months, but I always forget.