Andrew,

Keep an eye on it to make sure it does not become apparent on other leaves. My first thoughts would be roots, not drying back, too compact (soil) or needs a bit pot one size larger.

Make sure that this seedling is not staying too wet and that the tray underneath your pot is not holding water after you give it a drink.

Check that the soil is not staying wet too long. This will depend on what conditions you are giving it. If getting plenty of sunlight and good heat, it should dry back fairly quickly.

Overall the plant looks very good.

Rick

I'll keep an eye on the plant. The plant has a nice south facing window with direct sunlight for most of the day. I water every 5th day since it seems to take that long for the soil to dry out between watering.

I usually keep the plant on two skewers above the tray so that it doesn't reabsorb water (I took it off the skewers for the photo).

I am guessing that is a decorative top coat. What soil is below? The plant looks nice and healthy other then the spot.

You're right. The soil is whatever Out of Africa uses; I haven't repotted it.

Out of Africa will use a fast draining soil. They are not as humid as you, Need to stick your finger in there or go by the wet/dry weight. You only just got it so I would not up-pot it yet.