Welcome, and thanks for the input.
I guess i should have been more specific...
I also considered Mg-def, but since flowering is delayed about 4-5 days, overfeeding seems like the most likely case ( i've grown this strain 4 or 5 times before, it's just the ppp's that look like this). The yellowing is an older thing, fine now. I don't know ppm's, but i gave the girls a big ol' shot of vegnutes some time ago, perhaps after 12 days of 12/12 (it's now day 15). The problem has been getting worse since then, but it's not going terribly fast so i'm not that concerned. Might add that the leafes had the infamous claw-look, but that sorted itself out last night somehow (but the claw suggests Mg-def?). Anyway, i'll come screaming in panic if the flush didn't help.