The details. It is in the pot it came in by the window of a northern exposure window in the Seattle area. It is 72 to 64 degrees inside the room it's in with humidity from 40 to 60% It is in a smaller pot with a wick and I'm sure it's impossible to over water it due to there being no perched water in the pot, but I also don't water it like crazy due to it being in northern exposure which is little light for a banana.

The only thing I can think of for the black spot is that below the windowsill it is on, there is a baseboard heater that comes on and off. I have a piece of cardboard to try to protect the windowsill plants from receiving direct flow from that heater but I just reinforced it because there were small areas where the direct heat could still get through.

Any ideas or am I worrying too much?