KMSTR has the answer here. Just to add that the quality and timing of communication you get from the printers on this kind of issue is dependent on the relationship you have with them, and to some degree the price you pay.
I am guessing this is towards the lower end of the market, which may well be appropriate for this job. But you've not got what you expected, with no explanation, and likely to cause significant delay in delivery to end client.
Higher up the scale you'd expect an email or call when prepress try to impose the document.
A the top of the scale you might have an automated or human checking of your artwork for issues as soon as it is uploaded to the printer, allowing you to correct the issue immediately.