spacing in font depends on position on the page

[Xen]

I find that the spacing between characters of a font will change 
depending on what exact position the text has on the page 
(horizontally).

I am sure you are full aware of that.

The question is: shouldn't the spacing within a word remain the same, 
even if the spacing between words would change?

Here is an image: 
www.xen.dds.nl/f/i/screenshots/libre-office-font-spacing-oddity.png