read that as less than 1K in size for the 403. To achieve 120gb that file would have to be returned 120,000,000,000 times. I don't see that kind of activity on any of my sites for a single file, much less in a day and a half. :)
If you have data going out then I suggest you look again over jdmorgan's suggestions. Obviously something is inaccurate. Might take a look at what your 403 file is actually returning!