Savoy - that made me laugh!
OP - I don't have a child that age, so I'm not talking out of any experience here. If she knows you check, then perhaps you could mention it in a conversational way, "I saw you'd been looking at vaginas, what did you think?" - and mention the difference between caging and vulva.
If she doesn't know and you don't want her too know, perhaps a chat (sorry no suggestions on how other than "conversational") about women's bodies could open up the subject.
A while ago I came across a link (pretty sure it was on here) to a project where women posted pictures of their vulvas. It was not pornographic, but very explicit (photos of vulvas kind of are by default!) and blew my mind! At age 33, I had NO IDEA that women's genitalia differed so greatly. I'd seen my own, anatomical diagrams which were very similar to my own and the porn style which wasn't that different either. At the beginning I was quite put off (was looking on a big screen!), but as I looked I could start to see the beauty in the differences and was really amazed that I'd never known how much we differ.
I never had any hang ups about my genitalia, but I didn't grow up in an era when porn was so easily available and cosmetic labiaplasty was becoming more common (specifically to look more like the porn norm). It did occur to me that if girls were taught about the physical differences we have and to appreciate that, it might not be a bad thing in today's world.
Not sure if that really helps though. It does seem you need to be ok with the discussion first though as if you're not, she'll pick up on it and regardless of what you say, she won't feel comfortable being open with her questions.