Harry Potter bosses are deeply worried about their three main stars - because they're growing up faster than their characters.
But while 12-year-old actress Watson has noticed a change, she doesn't think there's anything to worry about - yet.
She says, "I've grown loads, and so has everyone else. I definitely see changes in everyone.
"We're the same age as our characters - nobody is trying to make us look younger."
Perhaps Watson's character HERMIONE has been developed to adapt to their growing up - she's set to go a little off the rails in the latest movie.
She notes, "You're going to see changes in Hermione. She actually becomes a bit of a rebel. She's not going to take anything from anybody else."