I got this sativa free with a batch of seeds, 4 weeks into flower, canna coco, gh trio nutes, this plant has been doing this since it was 3 weeks old, I was worried at first in case it spread but it didn't so I left it, I'm just curious to know what's causing it, it's perfectly healthy, building nice colas, the rest of the plants are fine, I've looked through the infirmary for similar symptoms but can't find any ???