My 5 year old twin knows but doesn't realize it

So this morning when I was getting ready after getting my girls ready for school. I'm in my room, my 5 year old daughter came in and stands next to me while I'm in the mirror, just drinking her juice. She then just stands there with a blank stare into space with a puzzled look. I looked at her and asked her was she okay. She said "yeah", with a puzzled face "but I think i heard something say mommy!" My freaking heart! I said said to her "wait you heard a voice say mommy?" She nods her head yes. I almost lost it. All I could do was hug her!!!! She then says "mommy why you hugging me?" Not in a rude way but just wondering way. Lol!!! I said because I love you. We're telling our girl this weekend on our first daughter's 7th birthday! 😭😭😭