is this light stress?

hi,i have this grow going,4 plants in soil,under 400w hps on day 36 since i went 12/12,some of the leaves of my plants,especially the 1s on the back right and front left have like yellow stripes through them,not in the direction of the veins but across the leaves,you should be able to see what i'm talking about around the edges of these pics,is it light stress?they ran out of headroom and got to within 9 inches of the lights and it seems to be the smaller weaker ones that have suffered,i've since sorted the light and now can go much higher and is currently 12" over the tops,
or are my plants suffering some sort of nutrient deficiency?i've given epsoms so don't think it's magnesium
anyway any help welcomed
thanks
stef

your plants look really good! it looks/sounds like you're experiencing yellowing off, totally normal. towards the end of their growth cycle, they start sucking the nutes out of themselves. this is the yellowing off. a lot of people start backing off on nutes and let the plant consume the stored nutes. this really helps in getting a great tasting end product in addition to a flush.

thanks for your reply,you reckon it could be that?i was gonna stop nutes next week for them to flush,i've grown this strain before and they never went like this,the whole leaves on the whole plant turned yellow at once after i started flushing,this seens like stripes across the leaves,i guess i aint too worried,only need to keep them alive another 3 weeks or so

give em a few days. on second look, it looks like maybe the lights crisped a few of your leaves.

dont worry your plants look sweet maybe one last nute blast before the pay off .

thanks again for the replies
i have some better pics of the yellow bits now,you can see how the tips are still green,then the yellow stripe then green again,apart from that they look good

Looks like nute burn to me.

thought nute burn but then it was only 2 plants and the damage occured below the bulb and not at the sides,(they've since been rotated) and only near the top