1Ds2 premature shutter failure? 38k shots...

I got an Err 99 today when doing rapid fire shooting (if the 1DsII continuous frame rate could be considered rapid!), had to remove the battery in order to clear it. Later I noticed a diagonal bar across the images. With a heavy heart I pulled off the lens and set the camera into sensor clean mode - got a shock to see there's a piece of black metal over the sensor, which I presume is one of the shutter curtains.

I don't know the exact number of shots I've done (which was the util that gets that from EXIF?), but there are 36,255 CR2 images on my drive and the shutter count - excluding today's few pics - is up to 8637, so it's probably 38,637 shots (or perhaps 48,637). Peanuts compared to the expected life of the shutter!!!

Does this kind of failure look typical? How much does it cost to fix? I really hope its failure hasn't damaged the sensor. :-\