Early leaves seem to be susceptible to damage, typically water and/or nutrients splashing onto the leaf. Why did you cut your big fan leaves off? For a small plant, they are the primary energy source and grow large to make a lot of initial food and energy for further growth. After the plant is established with plenty of other leaves, then it is ok to trim them off if desired, although the bottommost leaves I don't bother as they don't shade anything, they store energy and nutes, and they will usually yellow and fall off whenever they are "finished".
The big fan leaf that was cut by the twisty is OK, but try to leave your other growing fan leaves intact until the plant gets well established. They really help the plant out when starting up. Losing a leaf or two isn't uncommon at all...the problem you are seeing on the one leaf could be caused by a lot of things, but probably got splashed by something. As long as it doesn't start spreading to newer growth, you should be OK.