Orf quite likely if they have been on anther holding. Unless it is really bothering them, I wild just let it run it's course. It is viral, and they do get some immunity to it for the future. Just don't touch it, as it is transferable to humans and very painful (I have been told, never had it, but most of my adult goats have had it in the past). It will hang around your goathouse, and other goats may well pick it up. Virus similar to Herpes one in humans.