A product can be set up as both a stand-alone product and as a component of a kit. If the product is set to use asset files when it is ordered as a stand-alone product, those files will only deliver when the product is ordered stand-alone, not when it is part of the kit. The kit is considered its own product and so if it needs the asset files from the component those files will have to be created as a new asset for the kit.
For more details on Assets, please review this chapter: Ch. 058 Assets