Well let's put it this way, does the artist as the the creator of said art permit you to do such a thing?
If the artist is okay with it great! But if the artist is not okay with at all does he own the rights to the art he created? Does he have the right to permit you not to copy his things? That is the ethical question.
Did you have the right to do it without asking the artist for permission? What if one day the artist did actually want to make a profit off his work?