My buddy Pat picked up my guitar today and strummed a bit. After inspecting my rig he announced that I had mold growing inside, not your green kind of bread mold but a mold that looks like a little dust pile. I am fanatical about keeping humidity in my guitar but I guess I have let those little spores go unchecked. Mold actually eats the cellulose in the wood. I had no idea. I have to go after the little buggers with a diluted bleach solution per Pat's direction.
(Pat owns a commercial property inspection business and teaches mold identification seminars at hospitals and such.)