Typically bottom leaves will yellow when there is overwatering, and a lot of times the top leaves will be droopy, not necessarily yellow. And are the bottom two you are talking about just single bladed. I seem to lose those often. I am still unsure of what you are talking about when you say bottom fan leaves, I know you are not discussing the embryonic leaves. With overwatering there isn't much to do, but as long as new growth is not affected you should be fine. Good luck and Jah bless