HDD CLICK sound when picking up the laptop... by design?

[MBPnoob]

About 90% of the time, I am using the MBP on the couch while watching TV. When I pick up the MBP to move it around, the HDD makes a quiet "CLICK" sound... It does it more when the base is slightly vertical if that helps.

Is this by design? The first thing I thought it might be doing is preparing for a drop by stopping the read/write. Then again, it may be the ugly sound of a dying HDD.

Ideas?

EDIT: I should probably tell you what I have. Spring 2010 MBP. Specs are in signature.

 

[miles01110]

Its the sudden motion sensor i.e. normal.

 

[MBPnoob]

Its the sudden motion sensor i.e. normal.

Normal is good! I assume they do that to avoid data loss with a sudden drop?
Thanks BTW for the help! My heart has been eased.

EDIT: I am thinking about upgrading the HDD to a 7200 500 GB Seagate. Will the sudden motion sensor follow the HDD or is it part of the MBP?

 

[Fubar1977]

Yep, Miles is spot-on its the sudden motion sensor. I believe it`s a function of the Mac itself so it should work on a replacement drive.
Somebody please correct me if I`m wrong.

 

[GGJstudios]

Apple Portables: Advanced tips for Sudden Motion Sensor

 

[TopHatPlus]

haha isn't it great to find out that something is working the way its supposed to and that it did not up and die on you?

 

[MBPnoob]

haha isn't it great to find out that something is working the way its supposed to and that it did not up and die on you?

No kidding. I went from to