That's because the manufacturers of the cardboard weren't using recycled products in the mix. The cardboard may not have been properly cured as well. We used to run into such issues at the last place I worked.It is curious, I've loaded plenty of Accubonds that all came in cardboard boxes and never seen this before. I would have never guessed the cardboard was the issue.
The paper and glues used to manufacture the cardboard hadn't dried completely before being shipped.