We sometimes scratch our lambs (vaccinate them) for orf. They then will shed the virus. So even farmers who don't have cases of orf can be selling animals that can infect others.
It is absolutely not a reflection on your husbandry to have orf on your farm. Maybe your neighbours all vaccinate? And maybe you will want to, if you want to avoid it in future. Other factors include things that can break the skin on their mouths and noses so that the virus can enter - so clear any brambles, thistles, barbed wire, splintery wood and so on that they could damage themselves on.
I expect you'll have read up previous threads on treating orf? We do find that dipping their snozzes in a strong solution of Daz (and yes it has to be Daz specifically), then antiseptic spray, does help the healing. If you see secondary infection then the faithful blue antibiotic spray, of course.