When she said she was alone, before she even finished her statement, the maul was down a little, less ready to hit her with it. He didn't k now if he believed her, but for the second, she looked appropriately scared at the very least, which was better than her initial reaction.
"Wouldn't be the first time," he said, though it came out like a statement, not a threat. In truth he wasn't saying it to threaten her. She'd answered, and if she was telling the truth, good. Unless she tried to hurt him, she was safe from him.
He gave her space back, looking at the shelves then even if his awareness was still very much locked into her. He didn't want to wind up bludgeoned to death because he'd decided not to kill her first.