Not sure if this has changed over the years, but the shutter cycle rating for the D line is a lot higher than the rebel line.
The Rebels used to have a shuttle rating of 10,000 where the D line was rated at 100,000 shots. This does not mean that the rebel will break at 10k, it does mean that the D line is designed with a build quality for longer shutter life. My Rebel XT failed after 30,000 shots. Based on the 10k rating, I moved on and decided not to get it fixed. Had my 40D died at 30,000 I would have spent to money on a fix since it still seemingly had a lot of shutter life left in it.
not quite!
maybe you were unlucky, my XSi has over 100,000 clicks, still going strong