It turns out I've done yet another goof. When I did my boil, I left the lid on. Great! Now I'm expecting to have a beer full of DMS.
DMS is continuously produced in the wort while it is hot and is usually removed by vaporization during the boil. If the wort is cooled slowly these compounds will not be removed from the wort and will dissolve back in. Thus it is important to not completely cover the brewpot during the boil or allow condensate to drip back into the pot from the lid.
In other words, I pretty much messed up the entire reason for the boil. Concentrating the good, evaporating the bad.
Argh, yet another lesson about to be learned the hard way. I almost feel like I should just toss this batch and start over, but I'm probably too emotionally invested now not to ride it out.