I am having the same thing happen to my girls. One has been like this for a week or something like that. The other was fine last night , put it inside for 12/12 dark and when pulled out this morning it had lots of yellowing. I am very interested in what other people say. Mine are outside plants on 3 gallon pots. I am about 19 days into flowering and have no clue what this is or what it means. Good luck.:jointsmile: