That's ok, thanks for all the opinions! I see in my local craigslist there are khaki drakes close by.. maybe I can buy my lonely hen duck a freind instead of hatching one, as that seems a washout now...
It's probably more the time of year than anything. Fertility is lower in the winter. Eggs that are surprisingly old or cold can hatch, although that will reduce hatch rates as well. It sounds like fertility is more the culprit, but you might let them go a few more days just to make sure they are infertile.
Thanks for all the advice! I still have the remaining eight in the incubator, I'll check them again in a couple days. I emailed the khaki seller but haven't heard anything yet. It's almost chick and duck season at the feedstore..