hey dude, Cheese doesnt typically purple too much on the leaves but i have seen some phenos that do, purple pinstripes on the stem and purple petiole's are common for cheese, As mentioned if growth is good and steady then unlikly to be a deficiency. Keep an eye on how/if it spreads.
Just to clarify - you havent feed them anything for 4-5 weeks and gave them their first helping of feed today?? were you using enriched compost or some other media that is fortified with Nutes? seems a long time to starve them...
Yellowing is likley to be an N deficiency, N def will start on the lowerest and largest leaves first sending them light green and then uniformly turning them yellow, then the plant will shed that leaf.
If this is what youve seen then start adding veg feed regularly, little and often not to shock them, as theyve had no added food yet they may need to be 'eased' into a feeding schedule, depending on variables.
HTH and good luck with the Exodus - you got a top shelf strain there my man.