Hey Gogocrack,
This are the first signs of (n)itrogen toxicity, not mayor yet but it is there.
You also have a little bit yellow tips, normaly people will go for overfeeding but since you have low PPM/EC this is not the case.
With a Nitrogen toxicity your leafs will start getting yellow tips as well and start to claw.
Flush your plants a bit and lower your PH.
You use ph 6.7 which is in my opinion a little bit to high, try 6.3-6.4 instead.
Goodluck farming :)