Sudden isolated wilting.

[andrew001]

So, my Carolina reapers have been doing great. No issues. I was up at 6am, checked them, and they were fine. A few hours later, 1 leaf looked as though it was wilting. So I thought "OK, maybe it needs water" and I gave it a bit of water. The wiling has continued to progress. Any idea why this may be happening? It is only this one plant, in this top area, otherwise the plant as a whole, looks healthy.
 
Pics attached.
 

 

[CMJ]

Looks like sunburn to me. Is it in full sun and has it been properly hardened off?

 

[Bicycle808]

is it just the one leaf? Another possibility is, the stem to that one leaf might have been partially severed, so the leaf still clings to the plant, but it's disconnected from the plants vascular system. This kinda thing has caused me massive panic in the past, but it's no big deal. Just pinch that leaf off, and move on with your life