After a cold boot, the hard drive in my notebook jumps to 56? within an hour or so of idling. Is 56? a cause for alarm?

Notes:

• The notebook is on a flat desk and none of the vents are obstructed.
• The video card is currently at 55? and the CPU at 50?.
• It's a Western Digital 250GB hard drive.

• SMART reports the drive healthy but does warn that:

  

Edit: this problem had a very surprise ending. I inverted the notebook and unscrewed some of the panels on the back (there was one covering the hard drive, and one that provided access to the memory). I couldn't see any dust, so I simply screwed everything back together and powered it on... and it worked!

The temperature is now staying at 46?, and it feels notable cooler to the touch. So I can only assume that some internal fan was malfunctioning or something. Whatever the case, it's working now so I won't complain.

Edit: I have an SSD now, so temperature isn't as big an issue as it was when I had a mechanical drive.