Dark green leaves folding down

[NewGrow2019]

My leaves on top are dark and folding down. Three weeks in flower, Room temp is 75 the leaf temps are 72-74, humidity at 55%, HPS 600w, I've been on minimum nitrogen for 2 weeks and increased P-K. Is it getting to much potassium? Only two plants are doing this on top. Any advice is appreciated.

 

[NewGrow2019]

Feed them this morning and they straightened back up in about two hours. The soil felt wet so I delayed watering a couple days.

 

[AdaminCO]

You might want to read through emilyas “how to water properly” in my signature. There are two different techniques one for veg, the other for flower.