Looks like heat stress...

So my plant is exhibiting canoed leaves and leaf tips curling up, however the room they're in is never above 74 degrees and in my opinion they are neither under or overwatered. Any thoughts anyone?
{Super Lemon Haze (purple pheno)in 5 gal smart pot. Day 50 or so of flower. Under 960W MarsHydro. First grow I've used ocean forest with, and I almost killed them in the beginning because I normally use ProMix and I had no idea how hot ocean forest was. I thought I had them figured out, until a couple days ago when this heat stress looking thing started...}

And what's the humidity.

The humidity is almost always between 45-65%, however the last couple of days it has been 70% or so...

Humidity is way too high for a flowering plant for one... You are going to want to get that down to 40% or less.And probably raise your lights. The leaf curling is a sign of stress... If not heat then intensity.

That makes sense w the lights as only the indica looking one is exhibiting this...the two more sativa phenos are not experiencing the same issue. I will try raising the light and the two sativas tonight and leave the plant in question at the level it's at. As far as the humidity, I have a dehumidifier I guess I just didn't realize it was as important as it was. Guess I should quit being a lazy noob and get that thing running! Thank you for the advice!