[iBook] ibook corner cracks

[Todd Doerpinghaus]

I hope I'm not losing my mind.  I thought I remembered
reading some posts about cracks on the corners of
ibooks.  I searched the archives but had no luck. 
Were these cracks caused by knocking the book on
something, or was it something that just happened?  Is
it common?  My 900mhz g3 doesn't have any but we have
a few g4's that are starting.  Thanks in advance.  

On the other topic, my 900 mhz g3 dual usb has had no
problems since I got it.  

Todd