Leaf problem

Nitrogen deficiency, probably from changing to bloom nutrients too early in the plants life. The plant is taking nitrogen from the leaves in order to feed itself for flower growing. Next time don't change to bloom nutrients until there are small "budlets", cannabis still needs adequate nitrogen in early flower. At this stage you could give a dose of half strength grow nurients to boost the available nitrogen, but in reality, she is that close to finishing that I wouldn't worry about it. Remember too, what is showing now in the leaves is a reflection of what has occurred in the soil 10-14 days ago, so feeding now with half strength grow nutrients will maybe help a bit, but will not change the appearance of your plant. It wouldn't hurt your plant either, to feed it with one dose of half strength grow nutrients, before returning to bloom nutrients. Hope this helps, Organoman.