She intruded, and experienced the consequences. If she asks, just own it. I guarantee she will be more embarrassed than you.

This reminds me of them time my FIL went into my and my husband's bedroom with no reason and no permission. He comes out and says, "Hey, you guys have straps on your bed. Why do you have straps on your bed?" I look him straight in the eyes, and completely calmly say, "Well, when two people love each other very much..." He put his hands over his ears and shouted, "LA LA LA LA I DON'T NEED TO HEAR THIS."