You are lucky. Over at the Apple forums is a huge list of users with video problems, some of whom have had 3 iMacs in a row with the same video glitches.
It is starting to look like there are problems with the custom built models and their ATI video Cards.
I like the new model a lot too, especially now Macworld shows the custom models outstrip Mac Pros in most areas by quite a margin. But I will wait till Apple irons the bugs out first before committing.