Seeds in buds

I’m almost in my 6th week of flower and I started noticing seeds in some of the buds . It’s only a few plants. I check the plants everyday I have seen no bananas or pollen sacs. Any help of why this is happening would be great. Could outside air have pollinated them? Or some other outside source? Or can that plant be put under to much stress to cause this?

Stress
Outside pollen
Genetics prone to Hermy

Lots of things

This is the plant that I saw the most seeds on. I plants I have seen seeds on are all different strains. Is there a reason that only a few plants have seeds and not all of them. I have over 200 plants in here

Different genetics, respond to stress differently. I use all of my grows for edibles so I don't mind a few seeds for future grows. lol