Tiny black speckles on seedlings

[Tomatovator]

I potted up my plants to 2" cells a week ago and have them in cool conditions in the garage under Fluorescent lights. They look to be growing nicely but today I noticed several of the plants as having tiny black speckles on the leaves. The are very, very small as if the plants were dusted with potting mix. This is not the case and the speckles do not brush off. Ever hear of this? Are these plants soon to be dead? Should I be starting more seeds just in case?