iPhone 4 Retina Display Stuck Pixels - Common Issue?

The iPhone 4 I secured on launch day had 4/5 stuck pixels, so after waiting for o2 to get more 32GBs in stock I got a replacement last weekend, only to find the replacement handset has 2/3 stuck pixels too!

Is this a common issue? Bearing in mind the retina display makes it difficult to see these stuck pixels... I was using my new iPhone 4 for 5 days before noticing. It was only when watching a movie I could suddenly see them bright green on the screen (lots of shadows/blackness in the movie).

Please post here if it's a common issue, I'm trying to decide whether or not it's worth going back to o2 a second time for a replacement; if I've been unlucky I will, if it's a case of "look close enough and most iPhone 4's suffer this problem" then I won't bother.

Thanks a lot!