I have dealt with lots of accidental pollination. So much that i have researched the matter thoroughly. Let me share what i have learned.
Inside the calyx, or female flower, is the ovule. The ovule looks exactly like a tiny green seed. It is this ovule that is pollinated and then it grows and turns brown. It could easily be mistaken for a seed by anyone overzealous in a seed search.
If the herb is for sale, then watch the plants closely over the next two weeks. If they are in fact pollinated, you will see the seeds grow. Then chop them and it should be unnoticed to most folks.
If its for yourself, your probably better off letting them mature and then just picking out ripe seeds as you smoke it.
Hope that helps