Maybe it confused metric and imperial units?? The order form had text entry with a value of 2 with no units. The user assumed 2" but the print house assumed 2mm. Always always always show your units. I can still hear the voice of my high school physics teacher saying that.

It's equally likely that the unit was implied by other content around the input field and the model didn't make the connection (like "scale: [___] mm"), or perhaps the file format was just wrong and a human placing the order would have resulted in the same outcome.