Yow, I hope that didn't sour them to the holiday. I know, easy to joke now :) I had food poisoning once and it is decidedly not funny at the time.
I don't think so. We've had good dinners with them since then (LOL) and no one got sick. I do think it was the milk. There were rumors and articles around that time about salmonella in milk so that may have been it because everyone else was fine. What a memory!