nanners aren't a problem.. well much of a problem.
sacs can pollinate an entire room. a lone nanner doesn't produce much pollen.
tweeze it. scan for more. if not light stress at top, could be genetics and that would mean more coming. You can re-assess if it gets crazy.
there's lots of time to pluck them before they are potent. they don't release pollen when green/immature.
you should see them occassionally but should not be super common. the first strain i bought had a genetic nanner issue. i'd get 20-30 seeds per 300grams or so. It's annoying, but not a catastrophe.
throw out any selfed seed, imo. if you know the other plants do not have any nanners, seeds from those would be feminized... but again, if your plant hermed out due to gentics, it's not a good trait to pass down. but at least they wouldn't be genetically depressed like the selfed seeds.