I'm assuming that if you have a bag of nice buds with seeds in them, then it's likely that the grower didn't notice a male flower somewhere on what would otherwise appear to be a female plant, (because it's actually a hermie). What reasonable person would raise cannabis for sale and then leave obvious males growing among the females?
So no, I don't know why the buds had seeds, but I do know the plants those seeds grew into looked like ladies until it was too late.

You can buy quality seeds relatively cheap. Why risk the grave disappointment?