Was a ph problem. Guess I'm colorblind! Got my digital meter today and realized my tap water is 8.5, and my pH adjusted water was in the 7.3-7.5 area Lightly flushed the seedling I posted, and any others that were starting to yellow at the tip. Leaves uncurled on the older one, so I'm just going to leave it and give all of my older plants a light flush of correctly pHed water when they need to be watered. Hopefully everything recovers nicely.