Those aren't male nanners, they're female nanners. A 'she' has no male chromosomes to make male seeds.

If the strain is stout and normally nanner-free, Something happened recently to stress her. The seeds from these female nanners will be 100% female, but make sure they (the seeds) are mature before harvest.
If the strain is normally nanner free, try and save some pollen for future fems. Any lady would love her pollen. Pollen will keep in the fridge for months, barring any external moisture. Keep in an airtight, watertight container. Habitual underwatering is stressful, so this may be the cause. Would have to fill-out a troubleshooting form to try and pinpoint the cause though.

But if the strain is a known hermie, the hermie trait will be carried-on to successive generations, so don't save the pollen. :thumbsup:

Seeded calyxes' get a yellowish 'racing stripe' from base to tip. Hard to miss once you recognize 'em.

Now that he knows there's nanners, keep looking. The more seeds she makes, the less he'll end-up with in smokable yield. He might want to look in the buds for the yellowish nanners, too. Nanners aren't limited to visible nodes. Don't destroy the buds looking, though. This would be counter-productive.