Version:           0.8.4 (using KDE 4.2.4)
OS:                Linux
Installed from:    Unlisted Binary Package

Using the "Next" button finds results in order, but trying to go backward with the "Previous" button skips some previous results.

How to recreate:

1) Download this PDF: http://arxiv.org/pdf/astro-ph/0511180v1 (only because it's how I ran into the weird behaviour, and it may not be easy to re-create this effect, otherwise)
2) Find the 3-letter word: dra
3) Hit Next 4 times (it should stop on sigma Dra (sigma = greek letter))
4) Hit Next 1 more time
5) Hit Previous (it should skip the previous result, sigma dra, for some reason). 

It happens every time, and also with another result that is two clicks of "Next" away from the first "sigma dra" result.

Possibly something to do with the fact that the text is in a table? Just a guess; I don't know anything about how PDFs are actually formatted.