I've had one strain that did that the first time I grew it out. The clones did the same thing. The ones that formed the seeds were in the same grow box with 2 other strains and the other strains didn't have a single seed amoung the lot. Needless to say that hermie she/male is on longer being grown by me. The only positive is it left me with maybe a 1000 seeds that are probally fems.

These plants would hide the nanners deep inside the buds with only a few showing on the nodes late in flower, which I removed with tweezers and a spritz of ph'd water. Definitely washed down the inside of the grow room after these grows.