Man, I hate to be the one to explain this...

Anyway, check your plant(s) closely for new male flowers. Exposing the plants to any light during their dark period can cause female plants to create male flowers. There are other causes as well, like stress. If there are not too many male flowers perhaps you can pick them off.

Or, perhaps your male plants released a little pollen before you discovered them(?) Probably good to wipe surfaces with a damp cloth.

EDIT: Crossed posts. What he said. ^ :thumbsup: