your saying there is no anti aliasing ? this looks really blurry, like you said open it up check with a color picker and you will see the gradients....
I see gridlines on my iPhone, but only if I zoom in a lot. I'm guessing this is a case of "designed and exported on Retina display, for Retina display". Because yeah, in true 1-bit image there won't be a grey gridline.
There's something odd going on with that picture, though, because it has faint grid lines for the pixels. It's hard to tell what's anti-aliasing blurring, and what's a grid line.
If you open it in GIMP, say, and zoom in the grid lines are clearly part of the image. It's a mess.