If it is still fully functional, then you may have go away with it.
All Macbooks are equipped with a "Sudden Motion Sensor" which instantly parks the heads of the HD when it detects accelerated movement, sudden changes in position or intense vibration.
Hopefully you will be ok but check that everything is working correctly.
I just accidentally dropped my Macbook (120 GB Hard drive, 2GB RAM, 2.16 Ghz Intel Core 2 Duo, Running Mac OS X 10.4) around 20-25 CM onto my desk, with the left side tilting while it was dropped.
Is there likely any major damage or minor damage? CD Drive? RAM? Hard drive?