Hmnn, suspect if you had an expensive iPhone 4S with a yellow screen you might not be happy.
Imagine having a bit of an issue with a screen on an apple product you owned and being told it was something like 'normal variation'. Like the issue you had with your screen on your MBP 13", :
From your pos elsewheret:
Mid-2009 13" MacBook Pro that I purchased in August '09.
I've noticed that there are faint diagonal lines down the left edge and partially down the right edge of my screen, accompanied by a slightly smudgy look (on a white background, it looks slightly grayed). Everything is irregular, the extent of the smudged look, and the diagonal lines, while appearing to be spaced evenly apart (I haven't measured), are broken and inconsistent. Sort of like uneven length dashes.
You weren't happy then were you? Presumably your complaint was justified and not normal screen variation of any sort.
You are quite right of course, provided C39 yellow screen iPhone owners don't make any comparisons with other iPhones, or preferably any other phones, they won't see it as a problem. How does that expression run "in the land of the blind, the one eyed man is king".
Stangely, I still haven't had anyone take my offer of a swap - my lovely C39 yellow screen for their nasty cold version at the other end of the 'normal variation'. Do you have one to swap?