Dry leaves / dying.

Under watering will definately crisp up any leaves the plant was cannabilizing. But this late in flowering, most people aren't adding nutrients, so whatcha gonna do. The plant will use nutrients from its own fan leaves to continue feeding its flowers for reproduction. I like to leave more wiggle room and give nutrients longer in case there is still more flowering time needed, but some people do this to their plant anyways to make trimming pesky fan leaves easier. Long as it doesn't start to turn your flowers yellow.