My Seagate 1TB drive makes a sort of "spinning up" noise, feels almost like a car revving up, not sure if its similar to what you're hearing. The thing I've noticed most often is that it will almost always occur when starting up from power saving mode on the HDD.
It has sometimes occured while the PC is running as well, and the HDD sort of "lags". But it does not occur often and all my data on it is backed up for now, so I am not too concerned.