There area lot of different reasons a hen will stop laying. They don't all correspond to the molt or lighting.
First, I'd rule out whether something is eating them. It sounds like it is just her and the others are laying, so that may already be ruled out, but I'll ask an obvious question.
Has she been laying and just stoppped? I'd guess that she was laying a blue or green egg and you are no longer getting that colored egg, but again an obvious question.
I don't know how old she is either. Again, I doubt that is the problem?
Many hens cut back laying in extreme weather. My number of eggs drop a bit in the heat of summer and some hens really cut back in cold weather, even if they are not molting. I would not be too surprised if cold weather were it. I also would not totally rule out molting either. Some hens really show it when they are molting, but some are pretty subtle about it. It is not always clear-cut.
In answer to your specific question, even if she is not molting it is possible she will stop for the winter. You might look at her vent to see if it is large and moist or small and dry. If it is small and dry, she is not laying and probably will not in the near future.