I've experienced the same kind of issue with my copy. The only difference is that I've got only one irritating speckle in the viewfinder which is always noticeable. It doesn't look like dust, but Canon-authorized service center wants to charge $250 to remove the speckle. Official response from the service center is: "Dust and dirt in the block of mirrors due to careless use".
Attached image is a reproduction of how I remember the speckle (dark long line). Could anyone confirm that this is likely to be my fault or is there a chance that it is an internal oil / lubricant particle?