Strange noise from PB hard drive

My hard drive is making a somewhat high pitched whirring/screeching sound. It doesn't really sound alarming, but I've owned this thing since May and I've never heard it before. Incidentally, I reformatted and did a clean install on Saturday, but I don't see how that could possible have any effect on it. Is there something wrong with my hard drive?

I suggest that you take it to a service centre ASAP. The whirring is not so much a concern but the screeching is. Don't wait for it to fail as it normally will outside the warranty period. Excessive HD noise in a quite working environment also warrants a replacement. "Excessive" may be arguable sometimes though.