New leaf tips are twisting slightly also a slight ...

Your just past mid flower I would guess. Your humidity is fine for the temperature and stage of flower. The issue with the upper leaves is the start of light burn just back off your lights.(Buy a PAR meter to test how strong your lights are at different distances) You can see also some premature drying of the pistils on the bud from too much heat being given off by the light but it looks like you caught it in time. Loosing lower older fan leaves is perfectly normal so don't be concerned feed low nitrogen ,medium phosphorus high potassium to bulk up those buds over the next few weeks. You can also try using 1 tablespoon of black strap molasses per gallon of water a week you may need to correct the ph of the solution. It may help improve the terpene production and enhance your nutrient regime. In the last few weeks of flower try to keep your temperature under 80 F and lower your humidity to 40% or less if possible. Then flush with plain water for 10- 14 days to remove excess nutes from your soil to improve the final product. Hope this helps you out.👍