Fixing the "flash"

I figured out why I was getting a “flash” of white on the borders of my pages: I didn’t check the “Use Document Bleed” checkbox when I exported the PDF file.

By checking this box, the image is exported with the bleed area added on, which changes the document size from 8x8 to 8.125x8.125. When the pages are cut to 8x8, the bleed area is removed. If images don’t extend to the boundary of the bleed area, there’s a chance of a white “flash” showing on the borders, as happened in my case.