I have never experienced that myself but I have seen pictures like it before and read about it happening before. I have never seen a scientific reason for it offered before but there has to be one.
Sometimes things that would never be imagined by growers can be the cause for a hermi. One thing many growers do, and I do it myself, is to keep a fan blowing on younger plants, and some will keep a fan blowing on their plants for the entire time they grow them to deal with heat issues. As amazing as it may sound research has shown that plants grown outdoors in windy conditions will have both male and female sexual parts. I have wondered just how much wind it takes and if the fans we use might at least in part be cause for some percentage of hermis growers end up with?