Blue stains / marks on white Macbook casing

[WS82]

I have blue stains or marks on my white Macbook casing.
Have read up about the problem and saw some people talking about a similar issue back in 2006, and 2008. The problem seemed to lie in faulty plastic being used, amongst other reasons and excuses given. Some people had serious staining issues and received replacement casings.
My Macbook is a 2010 release, either Week 1 or 13 (hard to see on back), serial number beginning W801...

Just checking what the prevalence is of this, how bad it may be with others, and if anyone has had company/other advice on the issue?

 

[eman]

Most of the early macbook stains were tan to brownish in color. Most of these issues have been resolved to my knowledge and I've never seen blue stains on a macbook case. Try a magic eraser to remove the blue stains.

 

[johnnyham]

I get blue-tinted stains on my white late 2009 Macbook from time to time, especially on the rubber feet. It's usually because I have some ink on my hands or something stupid like that. Just clean it off with some rubbing alcohol or GooGone and it should come right off