Not at all... This is governed by the app_settings/mime_types_*.xml file (there's one for each OS), which has not been modified in over one full year...
Note however, that the issue might as well be the result of a change on the web server side, since the advertized mime type for files depends on it and may be changed by the administrator for each file type; i.e. you could, for example, configure a web server to advertize *.rpm files as RealPlayer movies or as binary files (for RPM Linux packages, for example)... Depending on what the server advertizes, the browser (or here, the viewer), will dispatch the file to different plugins (in the *.rpm example, a browser would either invoke the RealPlayer plugin, or propose to the user to save the file as a binary one).