It's been slightly difficult to get this discoloration to come across in photos, but here are a few attempts that I was able to take. You should be able to just make out the discoloration around the point where the two worrying leaves intersect with each other at the seed (it might be helpful to contrast against the remainder of the plant in the background):
Can anyone advise as to how bad of a sign this is? And/or what I should do going forward?
My initial thought has been that this might be happening because of under-watering. I've been using the "soak upwards" method of watering and had read somewhere around the forum that it can be beneficial to wait a little while before refilling the water tray after it dries out (the thinking being, as I recall, that less water encourages more root growth). I've been poking at the surface of the medium every day to ensure that it's remaining at least slightly moist (which by my own standards it's been doing), but maybe I've been going a little overboard with the water deprivation?
Another thought was that maybe this is some kind of fungus or mold?
Of course I barely know what I'm doing so I would love to get any other perspectives as to what might be going on here. Are there any corrective actions that I could adopt? Thanks for the help!