I've had many hard drives fail. Just recently a Western Digital hard drive in my server that was the second drive in a mirror started having issues with the ball bearings making a high pitched whining noise, going over into no longer spinning up. This is by no means the first drive to do so to me. Hard drive failures happen, the more of them you have, the more likely they are to fail at one point or another.
I've had my MacBook Pro for almost 4 years now and I haven't had the hard drive fail in it at all. I wouldn't be worried, unless you abuse your laptop while it is running most likely nothing will happen. Just make sure that you have backups, TimeMachine is excellent for that.