Well until I know if its something in my dirt thats causing negative effects on my plants I'm not going to be changing it just yet.

Something else that might help: This is only occurring, so far, on the smaller of the 2 plants... They both sprouted on the same day and have been under the same lights the entire time, but one is still much smaller and has now developed this weird colouring. Could it just be shitty genetics in the one seed?