2TB Passport - clicking vibration

Sometimes when I am watching a movie off of my 2TB passport, I can feel a “clicking vibration”.  I don’t raelly know how else to describe it.  There’s no audible clicks, and its more severe than the standard subtle vibration the device gives off.  It only lasts a second and doesn’t occur at regular intervals.  Is this something I should worry about? 

Check if the link below helps. You can also run a test using DLG to be sure. 

http://wdc.custhelp.com/app/answers/detail/a_id/568

http://wdc.custhelp.com/app/answers/detail/a_id/940