Etiquette on contacting past owner of your new RV

When we traded the Winnebago DP in to buy the bus, I told the dealer it was ok to give contact info to the new buyer. Big mistake! Buyer contacted me just to complain about things we had changed from factory and that we had kept cats in the RV while we owned it. Seems the dealer told them it was a no smoking/no pets RV. Told them the dealer knew we had cats, his grand daughter loved to play with them, and since the RV now reeked of dogs and cigarettes, didn't see where cats made much difference. :D