Yellowing on first "true" leaves

Unknown strain, mix up of seeds donated from people across Canada for project "Overgrow Canada". Looks like an Indica. Growing under 200w worth of CFLs, in hempy buckets with 100% perlite. They're on 1/3 dosage of nutes because I just transplanted. Notice yellowing on both of the plants first true leaves. This has me a little worried because it's not really consistent with descriptions of nutrient problems. I'm not well read on other problems at all. Hoping someone could give me some insight.

So far the information I've come across points at:

Still water sitting on leaves, magnifying light and burning them
Perlite dust?
Nutrient burn?

They're all otherwise healthy except for a few small yellow spots the size of a pinhead, which are few and far between.

i have the same issue. my first true leaves are yellowing.
i have the plant growing out of a jiffy puck, which i then placed into a netty cup with clay pebbles, and i put the netty cup into a pot where i have some water in there..
could this be the problem ?
the idea behind the sitting in a little water to keep moist is to prep the plant before i place into a hydroponic top-drip unit.
i never grew before, so this is my first try at it.

strain is autoflower - early miss from crop kings.