"But you can't remember making it." It's half-question, half-statement.

The signature is pretty solid evidence, but not foolproof. Someone else could have faked that. Clarisse herself could have done it. She's used to Riftwatch members seeing something they can't easily explain away and doing just that, even if the explanation doesn't make logical sense. Like Abby shrugging off the fact that without Clarisse around that means she and Ellie would have been willingly sharing a tent, or Benedict looking down at her name in the griffon keeper's office and assuming she must have faked it.

She isn't expecting Astrid to snap out of it just like that—it's promising that she seems uncomfortable, confused. That's more than she's gotten from anyone else so far. But Clarisse won't be holding her breath about it. She holds her hand out for the carving.