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This is normal. She is going through a growing spurt. Encourage the stretching. She may also be more hungry, may need a lot more sleep, allow her to sleep as long as she needs.
Make sure she is getting a lot of exersicing right now. Swimming, biking, running. All of this will allow her to reach her potential I growth.
She may even start getting a few aches and pains.sometimes they grow so quickly their bodies will have pains in certain areas.
Tell her about these growing signs so she will understand what is happening.
Do you have a place in your home were you are marking and dating her height? We have the one for our daughter on her bedroom doorframe. Fun to se how quickly she grew some years.