It could be a number of things. Hermies are hard to understand. It could be pH fluctuation, too much or too little nutrients. Are you growing in soil or hydro? Could be too much salt and that could be blocking nutrients which will stress the plant out. It could be a number of things that caused the plant. If the seeds got too hot or too cold before being planted. Something happened and it is so hard to figure it out. But, with enough research and patience it shouldn't happen again, and at least if it does you have the knowledge to troubleshoot the problem. I downloaded a book and will get you some more information on what could have happened and how to prevent it from happening again.