The bottom pitchers on both of my Nepenthes alata (i think, i'm on my third species claim for the same plants) are dying off. When I bought the plant a few weeks ago, they were doing fine. Is this natural? All of the upper pitchers are perfectly green, even though there are only one or two on each plant. One plant has also started growing two new pitchers. Is the plant dying, or are the traps probably just old?