Leaves take a while to perk up after lights on.

Hi guys. I have 2 gelato autos that are 35 days old. Have them under a ts 1000 on a 20/4 light schedule. They seem to me, that they are doing pretty well. I've noticed in the last week or so that the leaves perk up atleast 3 hours after lights on and have been sleeping atleast 2 hours before lights out. Just wondering if it's anything to worry about or maybe a problem somewhere that I'm missing.
Growing in soil. Over fed a Lil but nothing to bad.

Slight yellowing on tips of new growth on upper plant.

Any input be much appreciated. Tnx in advance

That's interesting. I can't imagine it being a sign of something terrible.

What kind of watering are you doing, and are you measuring your humidity?