Not sure what it's a sign of but the curling up of the edges of your leaves is a sign of a problem. I'm super new and have many more questions than answers but I thought I should say something. Don't take it as gospel though by any means.
EDIT - Just did a quick search here and found that it is most likely due to heat stress. You can try raising your lights and if you don't have a fan moving air over your plants yet that will help out
I'm also thinking your roots appear a little less then happy. When my plants have had issues the roots looked a lot like yours. When my plants have done well they are much thicker and many more longer hairs. The thing I notice most is the condition of the very tips of your roots. They appear to be shriveling and a little discolored.
Don't get me wrong because my last crop died so what the F**k do I know. My plants that just bit the bullet though had roots a lot like yours.
I've also used h202 in the past with great results but this time I've decided to go with
hydroguard. The
hydroguard will allow your plants to stay healthy at a higher water temp. I've heard that it can keep them healthy up to 90 degrees but i wouldn't try that high.