If it was getting too much sunlight, the entire plant would exhibit the condition you see on the lower leaves. The new ;eaves are the most susceptible to burning as they haven't developed much yet. Older bottom leaves are the first to give up their store of moisture and nutrients when the plant flowers and behave just as you describe. They turn yellow, or leathery, or droop. Phals have no pbulb in which to store food and moisture so the leaves and roots are where it stores it. Be very careful how much water you give it because overwatering looks much like under watering.