Once i had a similar situation. One of three gave seeds on all the buds of her. And was growing faster than other two (Started late, ended early. Total 2-3 weeks early). Other two didn't even give one seed.

You can't know like this if its hermie or not. What if one of the other two is hermied on you? I suggest check all of them for male flowers. If you find some then decide what to do. If you don't find anything just keep going like this but keep your eyes on them.

I don't think one time 20 minutes off can do this. If continuous, yes, may be.
Seeds will be femalized if the pollens from a hermie plant.