I have a 10 year old daughter that had a mole on her neck that was changing in color and border..My husband and I took her to a dermatologist and then decided to have a pediatic surgeon take the mole off and it can back negative...
I had melanoma 2 years ago and it looked supicious to me and the doctor but everything was ok..
I pray all is well with your daughter.
First off, you are doing the right thing. Getting it checked by a doctor is the surest way to put your fears at ease.
That said, the age in question, makes it fairly unlikely that she is developing skin cancer.
Have you evaluated based on the ABDE method? Is it asymetrical, is the border irregular, are multiple colors present within the mole, is it larger than 6 mm in diamter? If none of these apply, you very very likely have nothing to worry about. But take this opporunity to to get your whole family checked, especially yourself.
I'm not a doctor, but your little one is growing, and her skin is growing as well. It makes sense that as her skin grows to accomodate her growing body that the mole would increase in size slowly as well.
I have moles ive had since her age that have increased in size as i have gotten older.