This orchid is very light in weight. It was swinging in the wind all day last week and was hitting a potted Brassiavola. I hope this black striation is the result of the leaves being flexed and battered all day. I hope the pics clearly show what I mean.
Charles looks like it is merely vertical scratches from the excess swinging. I would leave it alone at this point and see if the mishandling will warrant cutting the leaf back. Still looks happy just a bit bruised.
If that is indeed what it really is. I am hoping. So far, it has not worsened nor improved. This is a good sign for trauma. I have also noticed that the points on the Brassiavola are blackened too. More evidence of trauma.