I keep an old stack of Mother Earth News around and they have a great column called "country vet". On p.95, issue 176 - November 15, 1999 there is a list of antidotes for some common poisonings. It lists Vitamin K for this particular one. There is a 2 part article, part 1 being in issue 175 about recognizing the symptoms of various poisons. According to the article symptoms could yet show up in the next 10 days.
Of course I also called Mickey & Beanie's vet to ask about signs and alert them in case he needed to be brought in for vitamin K. I just might take him in tomorrow for a precautionary shot, it'll be cheaper than waiting til he needs a transfusion.