Hi!
That wouldn't be your fault, as the assets were packaged fine on your end, as long as they weren't in the game's directory in a format that they come in, or any other format that is not protected. So the responsibility would fall on the person extracting them, as they wouldn't hold a license to use them.
Any additional protections on your end are not required, so it's all up to you if you want any additional protection measures.