It wasn't the pain that had caused the roar, persay, it was the surprise that his skin could be penetrated by fangs. He was indestructible! Or at least the Hulk had believed so. Of course when Lestat had pulled back the wound had closed very quickly.
When Lestat managed to get his leg out from beneath Hulk, the green beast moved to stand up and growled as he looked down at the vampire.
He reached down to grasp at the vampire, still willing to throw the creature as far as the vampire could fly. He deserved it for provoking the Hulk in the first place.