Etiquette on contacting past owner of your new RV

My husband and I were contacted by the buyer of our Foretravel to ask where we put the combination to the safe. :D There may have been one or two other questions, too, that we didn't mind answering. I also contacted the former owner of my current motorhome more than once with some questions and she didn't seem to mind. OTOH, calling a former owner to complain about issues with a used RV would seem a breach of etiquette.