Kill that fucker with fire ! It happens to us all. I had 15 clones herm on me best advise. Don't mix strains in the same tent because each different strain could potentally turn them all to seed which is what will definatly happen here unfortunatly. the main reason for herms is light leaks though so heres another peice of advice to never have this happen again. Simply flood the room you grow in with green light. This way if there are any light leaks the light getting in is green and cannot hurt your plants in thier dark period. Though I know its nice to show off your plants to friend and think "oh if i only open it once at night it be fine" wrong attitude we are all guilty of it though and we are also all guilty of going into the tents when we are bored and fucking about its just human nature I think to tinker with things ect. it could also just be a bad genetic and could be nothing to do with your system but that is extremely rare "apparently" though best thing you can do is get rid of this plant and hope she has not infected the others. Remove this plant very carefully if its next to others minimizing any movement at all and turn youir air circulation fans off immediatly. This will try prevent the pollen from spreading. After you have cropped your other plants you want to clean everything in the tent when i mean everything I mean every little crack crevice every item of equipment lights fans pots ect absolutly everything clean the fuck out of it espeically the tent. This way you should kill any remaining male pollen thats hanging around and could herm your next crop too as male pollen can stay active for anywhere fro 3-6 weeks so you haveto be careful. Highly diluted bleach is your best friend :) Hope this advice helps. as i said it happens to us all dont let it deter you my friend keep up the great work !