Nutrients-really odd issue...?

So I've got two different strains going. They are in week 4 flower. All plants received a full strength fox farm tiger bloom the sativa dom received a slight burn, but the indica doms are showing a progressive N deficiency that is working very quickly up te plant. They only have five sets of fans. Is this normal for some strains? The ones that are showing N def are very vigourously growing. I don't know what strain they are but it came from very high quality stuff.