I think it's due to the source material -- maybe a slightly underexposed photostat or dupe negaitive. You can see it in the way that the emphasized words (in bold italics) and other very fine detail tends to run together a bit and close up. It's subtle, but it's noticeable, particularly by comparison.

If you were to compare it to an original printed page, even with the spread of the ink on newsprint, you'd probably see a difference.

In The Back Of Beyond: My photography blog. Everything seen through the camera of my iPhone.