C 40D and "color maps"?

I have a problem (and big disappointment) with my C40D concerning the presence of "color maps" in jpg pictures with smooth color transitions. The picture below was taken to the largest jpg with lowest compression (fine) and Normal picture style. I also tried RAW, it was better, but in critical areas in the picture, the "maps" were still visible. My old 20D did not suffer from this. Could someone help? Should I send the body to the service? Thanx in advace!

Overall scene (resized):
http://forum.digineff.cz/file.php?47,file=471361

First crop (not resized):
http://forum.digineff.cz/file.php?47,file=471362

The second crop (not resized):
http://forum.digineff.cz/file.php?47,file=471363