you can tell it to run a "HDD Scan". but its only recommended if your worried that your HD isnt working properly. if it seems to be fine, then dont worry about it.
to check(all based on 3G iPod), simply hold the MENU and PLAY/PAUSE buttons to reset it. then when the apple logo comes up, press the PREVIOUS NEXT and SELECT buttons to activate diagnositc mode. from there you use the Previous and Next buttons to scroll down to "HDD SCAN".