Clones turning light brown/peach

On a couple of my clones the top leaves have turned a light brown/peachy color. Im not sure why, they're 16 days old today and roots are starting to come out of the rock wool. the clone shown in the pics has a tap root and another side root just appearing out of the rockwool but its still brown.

Anybody have an idea why this has happened? I know it probably wont affect the plant that much once it roots properly, but better to stop it next time.

could be from over watering, the plant being to close to the light, or feeding it to many nutrients

Good answer. Balls in your court shifter. Details??

ok well first ill get some pics of my clone box in a couple of hours. so u can see how close the lights are and the set up. but for now.

Lighting - I have 4x 23w CFL about 4 inches from the clones.

Water - They were in a dome for the first 2 weeks. so i just misted them twice a day, kept the humidity at between 80% and 90%.
now that the dome is off i water the rockwool once every 2 days.

Nutes - I only just started adding a tiny amount of B2 and veg food to the water i water the rock wool with. Im talking a few drops of each. maybe 100-150ppm of veg food.

Rock wool plays havoc with ph. Have you checked that lately? Quit using that crap and you may have better luck with clones. Oasis Horticubes are much, much better and easier to use than rock wool and no ph issues! And I am not sure where people learned to use a rock wool cube with a rubber band squeezing the shit out of it but you may want to drop that idea, too! It just doesn't make sense to do that if you understand the nature of rooting plants. They need freedom to spread the roots and with a corsett squeezing the crap out of the cube, how can roots grow and expand???? Think of having a bungee cord tight around your waste and you are trying to eat and grow. Kinda hard to, eh? And clones and seedlings don't need any nutes until very well rooted and transplanted into final grow medium. You run the risk of killing with kindness when you give 'em food before they can handle it. They don't need any nutes at the stage yours are in with the cinched-up cubes! Keep 'em in the covered seedling tray, damp, humid, (not soggy) and let 'em root real well. Good luck!

laskabud cheers for your reply. Thats not a rubber band, its just some loose string. Its there cause i opened the rockwool to have a look at the roots about 2 weeks in. just tied it with some string to keep it all together, probably wasnt necessary. also i should have left the dome on for a week longer.