I cannot speak to other desert tortoise species, but the California Desert Tortoise does hibernate and in my opinion the hiberation is required for nice steady, smooth growth. I know people who do not hibernate and their torts are fine, but I think you'll have a healthier tortoise if you hibernate him/her.
Also, something else I thought of for the original poster of this thread. If your tortoise is indeed a CDT then you need to be sure it is registered with the California Fish and Game. Registration is free and the form can be foudn with your local CTTC club or I'm sure you can get one somehow from the website. What you do is fill out the form, send it in and then they send you the original form with a sticker. The sticker is then afixed to the tortoises shell. Usually people put it on the belly or on one of the rear scutes. I have also seen hatchlings registered where the keeper keeps the tags on hand in case of an inspection but does not afix it until the tortoise is large enough to have the sticker. Also, if the tortoise is ever lost and foudn by someone, they will see the sticker, contact F&G and you'll get the tortoise back.
The point is: Register her if she isn't already!
Tortuga