Etiquette on contacting past owner of your new RV

I once sold a '73 Vw van to a woman. During her test drive it was immediately obvious she had never driven a standard. I questioned her judgment and tried to steer her away, but to no avail. About a month later she showed up demanding I buy her a new clutch, I refused. A couple of weeks after that I was in small claims court defending myself,(I won).
If I sell something it is yours, I do not want a relationship with you!