What’s wrong with these Dendrobium leaves

[sfunding]

I have three dendrobium plants exhibiting something I’ve never seen. Leaves are rough and white/gray. It doesn’t wipe off with alcohol on a cotton pad.

Note: I had to leave home suddenly for a family emergency and the south Florida humidity would have to be the source of water. I didn’t know I’d be gone nearly a month. Most plants didn’t suffer much, if at all. So, I’m hoping this is dehydration that can be remedied with time.