I bet this is something that can easily go overlooked if you aren't wise to it beforehand. Maybe not, but..
From the blog:
"To all artists and producers who are getting vinyl pressed it is highly recommended to order test pressings as plants will not accept any disputes if there are any problems with the actual pressing run. Test pressing are usually chargeable but essential to confirm the quality of the pressing before the main run proceeds. This is highly recommended because of the mechanical nature of the process."