A good A1C can depend on how old your daughter is. For instance my son is 4 and so his target BG range is 90-200. (As in we must treat for low at 90 or lower and provide correction for 200 and above.) The average BG then is 155 and if he were to have this all the time, it would mean an a1c somewhere in the 7s. We were told by our endo that for kids under 6, there is a risk to brain development by having too many lows - which is why the target is higher and that it does mean higher A1Cs (esp after the honeymoon period).
I think if your endo thinks it is a good number, I would ask at your next visit what he/she thinks about lowering it. They could have several reasons - for example, if your daughter doesn't recognize when she is going low, they may have a higher target to help prevent her from going low.
Welcome to Juvenation! It is a great site and I have learned so much here!