I'm no expert, but it looks sharply incised to me, as if done with a metal tool. Not much like the pecking and such-like of "normal" rock art. Then again, I've not seen it in real life. Just my first impression of the photo.
It is pretty much certain to be modern, there also seems to be two arrows between the two spirals and possibly some initials on the top of the stone too. Maybe someone getting a bit of practise in but its position screamed 'find me!!' so I think it might be a hoaxer trying to dupe unsuspecting tourists.