The ideal temperature for a week old chick varies. My chicks are currently about 11 days old, and I have them down to the mid 80's for temperature. It's harder to tell with a lone chick, but when you have several, it's easier to tell if they're cold because they'll huddle together.
I would try lowering the temperature to about 90 to start, then if she still seems comfortable, lower it a bit more.
Your brooder should have a warm side and a cool side. That way the chick can choose the temperature that is the most comfortable.