Ok, so I was making a repeat pattern in Illustrator today and got to the end to check that the repeat was seamless, when to my annoyance I noticed a faint white line vertically and horizontally (where the edges of the repeat were) when I used my swatch as a fill. Naturally I thought I'd mis-aligned something so I went back and checked everything. Everything was lined up correctly, and the square I used to crop the edges was exactly the same size as the artboard, and I centered it properly using the align tool.
It left me scratching my head a bit....
So I used the swatch as a fill again, and zoomed in a few times and zoomed out. I noticed that the lines were only showing up when I zoomed out to a certain size, but never when when I was viewing at 100%. I thought I'd check even further, and converted it to .jpg. I don't seem to be able to see any of the lines in .jpg form so now I'm wondering why they're showing up?
I even re-booted my computer, thinking it was maybe a temporary problem with the program, but it kept happening after the re-boot.
Can anyone shed some light on this?