While I do agree with PP's that this is a little unusual, I can easily see how this may have come about in a non-creepy way. For example, say whiterose is chatting about the family with grandma, and they get on the subject of her brother's new girlfriend.
Grandma: "Well, remember that girl he dated before with all the tattoos? What'sherface? Does NewGirlfriend have any tattoos?"
Whiterose: "I don't know, Grandma."
Grandma: "Ask her and see. I just don't know what kids these days are thinking!"
Whiterose: "Okay, fine Grandma."
So, is it busybody? Yes. Is it none of Grandma's business? Yes. But not creepy, controlling, or all that unusual to be honest. It's the kind of low-level nosiness that it fairly common in families. People are curious about the SO's that are brought into a family and I think it's fairly normal for them to try and "suss" out the new person. Do they have tattoos, do they drink, do they smoke, where do they work, how old are they - technically none of these things are anyone's business, and yet it's normal to want to know them nonetheless, particularly the longer the couple has been together.