RE5 Lost Nightmares DLC controversy

Ok, I downloaded this last night. I haven't played RE5 in awhile so I was excited for new content. I've noticed one very weird fact. My original RE5 (non gold edition ofcourse)game disc spins the whole time I am playing the new DLC content. Why would the disc have to spin at all ifthe DLC ison the hard drive? Normally I always install my game discs to the hard drive before I play. But I haven't installed the main RE5 game yet otherwise I wouldn't have noticed it. With all my otherinstalled games the 360 is silent. I really hope that the new DLC is really new. But if the disc has to spin it makes me think it was there all along. So is the "new" content just unlocked by buying the DLC. I have a bad feeling I was just had by Capcom.

My guess is the DLC still uses chipsets and items from the original disc so if you don't have it installed it will still need to access the disc to use them.