I don't know what happened but this morning I woke to find that only ONE of my salvias leaves (one of the new top leaves) had collapsed half way through.

It is really strange, its like it was thirsty but the rest of the plant is fine, it seems like half way through the leaf there was some sort of vascular collapse, the half nearest the stem is still upright.

Any ideas on what could have happened?

did that part of the plant get exposed to direct sunlight?

Is this a new cutting you ordered? Does it have an established root system?

The only time this has ever happened to my plants in 5 years or so was when they got direct sunlight for too long becasue salvia plants hate that..or my first ever plant I had that started to do that little by little and that plant eventually died, but it was in crap shape by the time it came in the mail.

It didn't get any direct sunlight besides maybe the hour it normally gets, I keep it in the same spot unless I'm watering.
I got a nice 8 inch cutting in May and it is now around 11-12in. It was root bound in the pot it came in and I'm sure it has some ok new rooting going on, it is an otherwise healthy plant.

I'm starting to think it was hit by something or that it may have gotten a little too humid last night?? It sort of looks like cold damage but I seriously doubt that.

OK this is getting weird. I've never seen a plant do this before.

I wake up today and the leaf looks much better but is still partially limp, as of now it is almost completely fixed. I watered it last night but I'm almost 100% that it wasn't a water issue because the rest if the plant wasn't even drooping.

Here's the strangest part, now the opposite leaf is doing the same thing, it has partially wilted at the tip and the rest is fine....WTF??

could there be root damage?

I don't think so, I have been doing the same thing with it the whole time. It has been thriving and there is a ton of growth. I haven't had any problems until yesterday. I topped it about 5 days ago but I only took off the tiniest new leaves, they were still pressed together and it was doing great and had a bunch of side shoots pop up.

I mean it is still in awesome shape and the rest is fine just those two leaves alternating "resting."