Thank you for your post.
I am unable to replicate the issue. I am using FileMaker Pro 13.0v9 on Mac OS X 10.10.3, HP LaserJet driver, and I have switched between All pages, Border, Reverse page orientation, Flip horizontally, Long-Edge binding, Single Hairline border, Two-Sided, etc. In all cases, there is no indentation.
What options do you have in Page Setup? (Page Attributes, Any Printer, US Letter, Portrait, 100% in my tests).
Let me know what I am doing differently than you so I can replicate the issue.