I'm running a droplet, the current public IP resolves to a domain which belongs to somebody else:
nslookup -type=any 188.8.131.52 ns3.digitalocean.com
Right now, the PTR for an IP is based on the Droplet's name, if the Droplet's name is set to an FQDN. If the Droplet's name isn't an FQDN, the PTR may remain set to the last Droplet's name that used an FQDN.
This is a...