I recently showed & sold 31 pullets & 3 cockerels at our county fair. I usually don't engage in this aspect of chicken-keeping, but wanted to use this opportunity to earn a little $$$ to finance the needs of the rest of the home flock. All the birds were 6 months old, the pullets just at the point of lay, in beautiful health & condition. They all won blue ribbons and 4 won trophies for best & reserve pullets. I sold 31 of them, 28 of those were picked up by their buyers the last night of the Fair. I brought the 3 unsold ones home, along with 3 others who had been bought but not picked up. These 6 were placed back in the pen with 6 of their former flockmates. Since their return they've all been doing/acting just fine, eating/drinking/pooping/laying normally. Yesterday I delivered 1 pullet to her new owner. She was looking/behaving well the whole while I was there. But today her new owner called to say she was now laying in her nest and wouldn't/couldn't stand up. Wasn't interested in eating/drinking. She had even laid an egg yesterday, but today she wasn't doing well. ???!!!?!?!?!?!!!!??? I didn't know what to say. I haven't heard any complaints from any other buyers, have heard only good reports. All the pullets I brought home have been doing well, and this girl was doing fine when I left her. I told this man perhaps she ate something she shouldn't have. That sometimes these things happen to chickens, they're fine one day & ill the next. He was concerned that she could have picked up some illness at the Fair & I said sure, it's certainly possible considering all the people, many of them chicken-keepers, visiting the tent. I told him that the birds are tested for good health before they are exhibited, and that we watch throughout the fair for any signs of a sick bird, and remove it. I gave him the number of a local vet who is knowledgeable about chickens, and also suggested he post his problem here on BYC. But if she dies, must I refund his purchase price? I really don't think I owe it to him. I sold & delivered a well pullet to him. None of her flockmates exhibit any of those symptoms. It's possible she swallowed something there that's affecting her today, or perhaps their dogs stressed/injured her when the people weren't looking. How long is her health my responsibility?