Feel free to play with it. I noticed one small area with a brush like streak but barely visible and clearly not as bad as my sensor. If my sensor was like that, i would not bother to have it sent in. But, that is not my camera...
Here's what I found on your friend's sensor. It's not that significant, but it does show that IT IS still there, nonetheless. I probably wouldn't be inclined to do anything about these marks. The point is, again, however, that there's something going on with the production of these sensors; some sensors just have these markings worse than others.
