Version: (using KDE 4.1.3) OS: Linux Installed from: Fedora RPMs IMHO, Okular need not diplay this message everytime it opens a PDF file (or any file, for that matter). It looks more like a debugging message. Imagine if kwrite, kate etc. also started displaying small popups everytime you openend a text file!
There is the option in the preferences to disable them (General -> Show info and warning messages).