Browser Tabs Leave Imprint After Being Closed Out Of?

This is going to be kinda hard to explain but it's really bothering me. Okay, I'm using Google Chrome and I had like three tabs open. When I went to close the last two, it left like an embossed looking print in the blue area. If I minimize the window it appears on the desk top too. I tried to take a screen shot but it won't show up on it. Anyone know why it's doing this?