Netsuite updated over the weekend and now our custom Shipping Labels are coming up as the xml script in our browser instead of .pdf like they were before. Any ideas? I've reached out to our customization company, but was hoping it was just a quick script fix or something that I could do until they respond.

Is it calling a SuiteLet or other script to render the document?

yes, it's calling a Suitelet

Can you see the URL the script is using to call the SuitLet? There was a change to the format of the URL and I'm wondering if that's related. It's a long shot but not sure what else to suggest without more detail. NS introduced new parameters in the URL, wondering of that's your issue.