Lettuce Seeds are Already Sprouting

I checked on my lettuce this evening and found that it was sprouting very well after only two days since planting. From what I understand about lettuce seed is that it is activated by light and moisture, so I don’t plant it very deep in my seed mix. I just sprinkle it on the surface, scratch it in lightly, moisten, and then put under my grow lights. Seems to work  very well.