Legal Question in Construction Law in California

It means nothing to you and therefore you have no need for recourse. As long as the work was done to code and as designed, without defects, it makes no difference to you if the subcontractor was licensed, unlicensed or doing something that didn't require a license (manufacturing). It might have implications for the general contractor with the Contractors State License Board, because it is a license violation to use unlicensed subs, but that is not your concern and nothing you could do anything about anyway. If the work is defective in some way, your recourse still is almost entirely between you and the general contractor, although in some circumstances the subcontractor might have direct liability to you, though those are not common. The subcontractor's license status would be relevant to you in those uncommon cases.