mysterious blue and white stripes?

I realize this is a minor issue, it's mainly just an interesting phenomenon to me. I read in Macworld that in Finder windows now we're using blue and white stripes to help make it easier to distinguish items. I do not have these stripes in my windows. What's more interesting is that I do see evidence of the stripes--within the drop shadow of any window I can see stripes in an underlying window, but nowhere else. Looks like a software glitch to me, but I have no idea what I could do to fix it. No one else seems to have reported a similar problem, but I'm wondering if other people are having the problem but don't realize it because they don't know that their windows should include stripes. Anyone else notice this?