As usual, this involved several aborted "oh I should take care of that" moments, a few times of noticing people talking to me on AIM, and so over the course of about ten minutes my plate and condiments gradually migrated to my computer.
Finally ready to eat, I picked up the two knives and -
Yes, somewhere along the way my fork had turned into a knife.
I have no idea where the knife came from. I couldn't figure out where the fork had gone. I suppose it's possible I just picked up two knives to begin with, but that seems unlikely, I usually get the right silverware the first time out.
The world may never know.