This looks like the first set of leaves and can be normal. Keep an eye on the seedlings. They should be okay. Do not overwater and keep the lights 1-2 inches from the seedlings. Wait until the top of your growing medium is nearly dry before watering. You can either apply water to the surface or allow your growing medium to wick up water by setting your containers on a shallow pan. Water to keep the growing media moist, but not wet. http://extension.umd.edu/hgic/plants/seedling-care
Send us more photos if you notice additional symptoms.