One entire female plant and I fine one seed.

I'm trimming bud all day and I get down to my last girl, a White Widow from clone. I killed the males long ago. I hit a hard spot on a bud and I pull out a seed. I couldn't believe it. I have trimmed more lbs than I care to remember and I have never found a seed.

So what gives? It had plenty of rock hards buds so not a hermie for sure. Anyone else have this happen and if so, did you plant the seed?