Brown spots

I'm in my 4th week of veg and a few of my leaves are starting to show these brown spots. I use happy frog soil, House & Garden nutes according to their chart, 82*F, 1500ppm CO2, 50-60%rh.

What are these? I don't see any bugs. I wonder if they are from overfertilization, I mix up 10 gallons of nutes each week and I have a little left over so they get that in between feedings instead of straight water. I would have thought they would turn color though and almost all my leaves are nice and green.

my plants are having similar issues as well , but 20x worse :/

not too much to worry about there.