Mid level fan leaves yellow and rusty

Plucked these fan leaves from 2 out of 83 healthy plants. I suspect CalMag def, but I am open to suggestions. Yellowing and rusting from tip to stem.
BM7 soil
HLG 550 v2s
Temps 68-79 full cycle, Hum: 45-65
Nutes: Tiger Bloom at 70% every feeding.
Rust does not rub off. Under the microscope, it is clearly dead spots in the tissue.
PH: 6.8, 1 week into flower. The rest of the plant upper and lower look fine.
Cal Mag deficiency?

posted a photo to buddy.kindbot.io
Buddy suggests calcium, magnesium, manganese based on spotting and yellowing

Thanks!, I’ve started feedings of cal/mag, waiting to see the results. Thank you!