I'd walked over quietly, but not so quietly he'd laugh if he caught me. He seemed engrossed in what he was doing, but I'd seen him apparently totally oblivious to his surroundings in the backroom of Babylon, and later be able to recount every guy he saw, what he was wearing, and how good or bad his technique was.
He might have known I was there, though, because he was stroking his dick languidly, one hand braced on the tile wall while the water poured in little trails over his skin.