it is if you claim it as your "intellectual property". If you deny that the original image was yours, it's not, and it's not even an issue until you try to make money off it really.
it might be but no one will care. if I saw someone in the lineup with the mona lisa on their board I wouldn't call up paris and tell them to get their asses over here.
my girlfriends a pretty rad artist, like went to a art school in toronto and shit, so shes doing the art work, and its a picture by chilithom called missocles, its on his website under the summer gallery