The right reasons? Her letter of withdrawlal Click Here emphasizes only one thing. The defense of secrecy in the Oval Office which might have been breached by inquiries during confirmation.
What is so precious secret about the executive office that she had to fall on her sword to keep it hidden?
The othe rpossibility of course is that the letter is all Bush-wah, and Georgie just asked her to back out so he could save some ugly face.