Not a issue for me, but I did see some of what could be "screen door effect".
1st: Lower resolution when panning a photo.
I was looking for a background image, and notice that when I really zoomed in, and panned that you could see pixelation during the move, and when the movement stopped the resolution was increased, and the pixelation would fade away. This is obviously a software choice as a low res image is easier to move.
2nd: Low res gif type shading.
some of the graphics us the old shadowing technique of lots of contrasting dots close to a solid color, and fading with decreasing dots as it blends into the background. This is a screen door effect of the graphic itself, not the display. The very high resolution of the display just makes these low res transition dots stand out.
3rd: Graphics at a non-native resolution of the hardware.
This used to be a big problem with early LCD pc displays. If the output of the graphics card was at a resolution that was not at the same number of pixels height or width wise with the hardware of the screen, then trying to match the two would cause a pattern to appear. I am guessing that the new QHD displays at 960x540 may do some strange things displaying an original background designed at 800x400.
4th: Morie patterns related to #3
I remember once scanning a photo from a certain magazine once (don't ask which one) when I first got a scanner. The resultant scan had a terrible screen door pattern when scanning Magazine photos but did a terrific job scanning in original photos. The magazine photos are of course printed with an array of tiny dots that you do not see with your eye. But since the scanner also recorded a series of tiny dots when these dots did not perfectly align then it would make the "screen door" or Morie pattern. I would have to software "blurr" the photos to get rid of the pattern.
So when applied to the phone world, it could be that much of the screen door effect is because the photon does have a high resolution screen, and a different aspect HxW ratio than much of what original android graphics was written around. Other phones may either just not have the res to show it, or it is blurry enough to mask the issue.
Everyone will have to find the display that does it for them, but any phone no matter the technology or resolution could have these problems. Life is a series of compromises.
Me I am still damned happy with my Photon. The screen door just keeps out the mosquito.