I got a 24-inch Intel iMac about 2 months ago. It's been great so far, but recently I set my desktop background to a gray gradient, and I notice some banding in the tonal shifts. I was able to create a different gradient in Photoshop and the banding was less evident, but it's still there if I look hard enough. Most other gradients appear fine; e.g., vertical gradients (mine goes from top to bottom) have no noticeable banding.

I tried to find a solution, but none of the suggestions I found seemed to have much effect. Adding noise or blurring the original gradient didn't work, and I wasn't able to fix it by adjusting my monitor settings (though I didn't try much in the way of adjustments, since I don't know what I'm doing). Only after I created a new gradient was the problem affected, but it still didn't go away completely. However, I do notice that all the gradients I looked at, the banding always looked different and sometimes was hardly noticeable.

Is this something common to iMac displays or LCDs in general? I've never had an LCD monitor before, but the ones I use at work (20-inch Apple Cinema Displays) show no banding with the same type of gradient background. Should I be sending the iMac in for a replacement or repair?