We had a winter once that the power kept going out.I ended up with a hermi.I grew the seeds from this plant and they all turned out hermis.All of them.

I have freind who did the same over the last two years.All hermis

When they bread feminized seeds they basicly stress the female to produce female seeds.If the genes are not stable enough I would think you could end up hermi.

Could it be that you have simply planted a hermi seed?