Semi-circular damaged leaf edges

[Joseia]

I hope this is just paranoia, but two of my orchids are developing some kind of damage along the edges of leaves. First pic is of a phal leaf with the damage: a dried-looking semi-circular patch basically eating away at the leaf from the outer edge. There is a very thin black ring, like a half-halo, near the still green part of the leaf. A part of the leaf is actually gone, it looks like a half-moon hole. Second pic is on a NOID dendrobium. The black spot in the upper left part of the leaf has been there since I got it and hasn't grown or changed at all.

Both plants are growing very vigorously with new growths, roots, and the phal is growing a spike that is now about 12 inches long. Whatever it is, it is very slow - the 'wounded' area is not growing very fast at all. No sign of any pests. I had a spider mite outbreak on some houseplants a little while ago, but never saw any on the orchids, and still don't see any sign of bugs.

Any ideas?

[Leafmite]

If the spots haven't changed, they are likely nothing of which to be concerned. If you have had spidermites on other plants, it is a good idea to check your plants and orchids every week to make certain you've got them all. This post reminds me that I need to get some horticultural oil so that I can be prepared if I have any problems this winter.