white spots on the stem

hey guys, my plants are coming on good, one plant i planted after the first two is already bigger than them!
But now on all my plants there are white specs on the stem, which makes me think they are part of the root system and therefore my plant needs to be re-potted lower.
any ideas or is this the case? I can take a photo if required but I thought this would be a simple thing so didn't bother.
The plants are like 3 weeks old now, and they are overstretched due to bad lighting at the start of growing.
Should I be repotting them now or what?
Cheers guys, Moley, PS they are starting to smell as well, bit suprising so early? its super skunk no.1 so is that a big suprise or what?
Cheers guys.