I think I've been coddling my sprouts a little too much. They're over a month old and haven't seen any direct sunlight. Each of them has a set of secondary leaves, and are seemingly healthy and eager for more growth. So, I've started giving them small doses of direct sunlight, and much more outdoor shade. I know I'm crazy, but I'm convinced that a few of my sprouts grew a tiny bit from their time outside today.
Also, since the soil is probably starting to lose its nutrients, I gave each seedling about a tablespoon and a half of 1/4 -strength fertilizer (24-8-16 water soluble from Giant-Sequoia.com). If they don't react negatively to the treatment, I'll continue to apply small amounts of diluted fertilizer every seven to fourteen days.
I also tried out watering the sprouts from underneath, which seemed to work well. To do so, I placed the block of nine cel-packs in an inch of water, and waited for the top to become moist (fifteen to thirty seconds). I'm going to try this out every other day, rather than spray the sprouts twice a day with a spray bottle.