What you are seeing is called Stitching and it's a flattening artifact. You are lucky it doesn't show on your home printer if you are printing a flattened PDF.
Is there any way to build this without the transparency?
I could paste the graphic with fade in photoshop and match the background.
The think is, the front cover for example has more transparency and layers and prints just fine.
Does stitching occur more on lighter objects and backgrounds?
I obviously can't trust the printer we're using to handle the flattening so we'll have to use a workaround.
This is a random thought -- I don't use printers who can't handle transparency -- but I think the stitching is usually along the bounding box, so if there's a way to make the frame larger that might move it off the page.
You should ask you printer what he is doing.
- Does he open your PDF in Photoshop?
- Does he export and convert it to EPS? ANd convert it to a different color space?
Or does he print your PDF directly, which is the correct method?