Does she know something I don't?

Marissa came into the house to wash the dishes and she was a bit grumpy about it, so I was talking funny and hugging her and trying to cheer her up. She eventually smiled, and laughed, so I picked her up in a hug. When I put her down she said, "Soon you won't be able to pick me up." I confidently said, "Oh, I'll always be able to pick you up." She confidently replied, "Not when I'm 30. You'll be in a wheel chair."