The leave changes may be caused by one of these factors...
Over-fertilizing - the most common cause of leaf cupping aka leaf margin rolling, leaf margin burn, and leaf tip curl/burn is the overzealous use of too much plant food in relationship to factors such as plant vigor and rate of growth. The first unit of a plant to show moisture stress is the leaf at its margins and/or tips, reflected by margin rolling (cupping) or burning. A hard, crispy feel to the leaf frequently occurs as well, as opposed to a soft and cool feel of a happy leaf. When you have a high concentration of salts in solution (in the root medium) compared to the salinity levels found in the plants tissue, water is actually drawn out of the plant across the root gradient in order to fix the ppm imbalance. IOW, this is a natural, osmotic response that serves to equalize salinity levels on both sides of the roots epidermal gradient. Back off on the amount and/or frequency of plant food. Too much plant food can also burn the roots, especially the sensitive root tips, which then creates another set of problems. Note - as soil dries, the concentration of the remaining salts rises further exacerbating the problem.
Underwatering - not only is the plant now stressed due to a low supply of adequate moisture, but carbohydrate production has been greatly compromised (screwed up). Step up the watering frequency, and if need be, organic growers may need to water from the bottom up until moisture levels reach a norm throughout the medium. If the pot feels light to the lift - its time to water. Dont wait until the soil pulls away from the sides of the pot or leaves droop before you water. And of course, leach once in a while to get rid of excess salts.
