Is this a nutrient burn?

Hey there. That seedling looks like it's few days old. Are you using seedling specific soil, like Light Warrior or Espoma Seedling Mix? If you have not fed Her anything, then it might be the "hotness" of the soil. Rich super soils are loaded with micro-nutrients, and do not require additional feeding for about 30-45 days. But like FoxFarm Ocean Forrest, it is too hot for seedlings or germinating. If any of these are true, I would just try and ride it out, till She gets to veg state. She will then be able to handle the micros. better. Watch your watering, during this time as well. You should be misting (soak soil) her at least a couple times a day. These are a lot of assumptions, on my part, and by eliminating these challenges, you give your plant the best start, when using soil. This just my humble opinion here. Good luck, and good growing.