Possible heat stress!

I have never had this problem on any previous grows. Could this be heat stress, bugs, fungus or what? any help please from some experienced growers.

looks like a burrowing pest..... not sure I run a very clean enviorment and have personally only ever had spidermites which i can expertly combat. the pics are not so clear to me but appear as thrips or leaf miners... I would get some neem oil to combat them but removing the leaves affected will help also as they tend to be protected.... neem does well penetrating though.

Looks like a it could be a ph issue (yellow speckeling and contorted leaf blades), or maybe lack of oxygen to the roots which is essentially over-watering. I also see your leaf edges are up, that means the plant is trying to transpire, that is caused from a humid grow room and/or over watering.
Whats your water temperature at, you could have warm reservoir temperatures?

looks to me like it could be a healthy plant?
maybe?
just a healthy plant riding the edge of nitrogen abundance?
experiencing vigorous growth, following a heavy rooting phase where it's encountered fresh soil?
maybe?
just a plant, being?
relax - are your temps over 85?
is your humidity under 25%?
are your 1k watters less than 4 inches from your plant tops and uncooled?
i doubt ANY of these circumstances are met
the FIRST sign of MILD heat stress is a hard upward curling of the serrated edges of your fan leaves

go in your room
water your plants
turn offf your fans
watch your plants as the temp rises
let it hit 85
kill your lights crank your fans wait 5 minutes and turn your lights back on
no longer wonder what heat stressed plants look like

minor pest damage maybe btw - nothing i'd freak about just the same - thrips make those scratches though