Text gets slightly distorted when exporting very long documents

[BillKerman1234]

I'm currently in the process of transcribing a web serial I like so that I can print a physical copy for myself. So far I've got the first 300 or so pages done, and I've noticed that when I export the file as a PDF there are very small distoritions/compressions in the Y-axis applied to the text. A picture speaks a thousand words, so here:

I've tried changing the quality settings in the export menu and nothing happens. The text in the InDesign file itself has no issues, so I presume the problem is in the export process. I'm currently using Version 17.0 on a 64-bit PC running Windows 10.

[BillKerman1234]

Okay, I just tried exporting it again a few minutes ago, and the problem appears to have gone now. I have no idea why though, and it's possible it might happen again in the future, so I would still appreciate any insights you can give me on why it happened.

[Luke Jennings3]

Are you viewing the PDF in Acrobat or Reader? I suspect there was nothing wrong with the PDF. Some non-Adobe PDF viewers are not very good.