line spacing with upgrade.

Hi.
I just updated from 5.0 to 5.2 and text that fitted on one page in 5.0 now flows onto a second page.
I can see visible creep down the page (against that produced in 5.0) when I line up against some images. The text is in default style.
What happens if the default style changes slightly between LO releases.
Should I always be using a custom style to preserve layout.
steve