The theory when the 10 frame deep box was invented was that it was an adequate size for a brood nest. Some queens will not lay more than 10 deep frames of brood. But sometimes, some will lay two mostly full, or lay parts of three full. I wouldn't worry about it. The bees will do what they think they need to. If you think they have started filling the bottom box with honey and haven't opened up the top box for her to lay, I would remove some of the honey frames and put in some empty frames for them to draw and the queen to lay.