no not at all. The leaf looks totally normal everywhere else but then there will be random patches where the top layer of cells have just flaked away which obviously leaves the bottom layer exposed and they die as well. everything stays green though
I would suspect thrips. I know you already said no bugs, but these things are tiny. I have pretty good eyes and I can barely see them, sometimes, most times not. They have a snout like head they dig into the leaves with and suck the sap out. It leaves the foliage with silvery looking patches because there is no more chlorophyll, and they eventually die.
I am battling them myself right now. Got some lady bugs and they slowed em down for sure, but they didn't get rid of them completely. I just got a bottle of Spinosad, which is supposed to get rid of them. It is a natural bacteria that disrupts their digestive system and kills them. It's harmless to the plants and people, you can look it up on the web.
Hope that helps.
GS