@JWChibi Your point is valid, but the way I saw it was more like a concerned parent. While officially she's only a servant, a lot of times these older servants may have been with their masters since infancy and sort of view them as a cherished child of sorts. Rather than not trusting the Duke, I think it comes more from a place of concern about this unknown woman he's suddenly married. Plus Ivona's own maid made misleading comments about her which would only amplify that concern. Even though in a way she is doubting the duke, rather than looking down on his choices I think she was worried that maybe he's being deceived or manipulated. Before Ivona suggested the contract they were essentially strangers and because its a contract it wasn't a normal courtship and moved pretty quickly. She also comes from a family of much lower rank and she was previously engaged to another man. It's not surprising that she may have some doubts about Ivona and her intentions.
She may not have a "right" to test her, but if someone you care about suddenly got married to a person you've never had the chance to know (and seems maybe a lil fishy), who wouldn't want to prod and test them just a bit? At least that's the impression i get at this point 😅