I figured it was probably magnesium or something, so I have been feeding Botanicare CalMag for the last month or so, a full dose every other watering. Seems to have improved a bit. July was a busy month for me, so they got a little neglected as far as nutrients go. They had just been transplanted into Fox Farms Ocean Forest in late June, so I wasn't expecting to have to deal with anything nutrient related for a while after that.
I got from my seeds from Getaway Mountain in the wintertime. I believe their site only runs in the late-fall/early-winter (I guess when that years seeds are ready) until springtime (I guess when they run out of seeds). It's a small company that has a greenhouse, but does mostly guerrilla grows outdoors in the Bar Harbor area. You pick your seeds from their small selection (I wish they at least gave more info about each strain), print out an order form, and mail it to them with your cash. None of their strains are feminized, but all of the several plants I started with this spring showed sex within a month. Also, they hook it up; I ordered a tenpack each of two separate strains, got 20+ each of those strains, plus 20+ seeds of a third strain I hadn't even ordered.