OSX keeps checking my DVD-drive, every so often I hear a small noise and the led on my DVD-drive lids up for a second and then dims, even though there aren't any disks in there.

Since the noise it makes is very similar to a failing harddisk I first assumed my harddisk was failing.
Even though I'm happy it isn't it is still working on my nerves, so I'm wondering if this is normal, and if I can stop OSX from doing that.

If anyone is wondering, I'm talking about OSX version 10.5.8.