I have this happening also,
It started with one plant a day after watering all outhers were fine.
I went Fishing Today for the first time In two years to my favorite salmon hole.: and left my girls alone for the first time. Came home and found that seem to be happening on more leaves on outher plants.
since i left this am and everything was fine added 5 cups water only to the three in question, near dehumidifier, they always use more H20. and planned my watering after lights came on with the foxfarm nute program for 8week
9week schedule using their dirt i might add. everthing has been perfect up untill this.

can anyone help stinkbudd and RoosterTail solve this fast, 4weeks to go????
thanks in advance,