VPD

I have been doing pretty well keeping in the VPD range at each stage of growth. However the last few days the leaf temp is higher then air temp? Still in range with VPD. But what is causing this? Are they not transpiring? Air temp is in general 74-77 and leaves are anywhere from 77-84. To much light? PPFD in middle is 800.

Lights could be too close.... LED's or CMH? Here's a pretty cool interactive chart you can mess around with.

https://vpdchart.com/#F,56,80.6,79.7,0

LED

I think you're fine.. but you might want to pull the lights up a few inches and see if your LST comes down a little.