Well, that escalated quickly.

I realized this morning that the soil was rising up where my sprouts were growing. When I moved some of it, I found that a lot of them had already grown several inches under the soil, rather than pushing through. The only annoying thing is having to wash them a thousand times to get all the soil off them (because some bits kind of get tangled into them). Less than a week since I planted them, I ate my first bowl of sprouts today with a little bit of salt, pepper, and olive oil.