Do you notice any new vibration when it is making the noise, and is it constant or occasional. If you are getting vibration the heads "could" be making contact with the platter, and you will want to backup what you can before it fails. Could also be a bearing starting to go. You should go to the manufacturers website and see if they offer any diag tools to see if that reports any problems.
What he was asking is if the mounting screws have become loose, which can lead to vibration and odd noises.