I wouldn’t, no, because you’re openly acknowledging somebody else’s art, or your own, for that matter, and putting it together with the art of others as a means of enhancing it to fulfill one specific purpose. Plagiarism would be if you took one person’s art and published it as yours as it is. Or if you are using somebody else’s character in a drawing of your own, it would be simply a lack of acknowledgement to the initial creator.