It's less than 2 years old and has not been damaged or abused or anything like that.
It comes as a great shock to many people that moving your laptop while the hard drive is moving is abusing it. While rotating, the G tolerance of the drive drops dramatically, and the heads can contact and damage the surface.
In any case, my experience is that non-stationary drives have a life expectancy of about 18 months, so you are right in the ball park. If you are getting a replacement, consider a Hitachi Travelstar. They have higher G ratings and quieter operation than most any drive I've used. They also have a much higher load/unload rating, so you can spin them down more frequently when mobile, to avoid damage.