Apparently, redirects in categories are always meant to appear in italics. In our MediaWiki (1.13.2) this is almost always not the case. This is not a problem, but sometimes they suddenly appear in italics and then after a few minutes go back to non-italic font!
This is not a browser issue - when it occurred I checked it in Firefox & Chrome and saw the same results (and saw it resolved in both a few minutes later).
Is this a skin issue? I'm just puzzled why it occurs infrequently (about once every few weeks) and then only for a few minutes...
What does your job queue (Special:Statistics) look like when this issue occurs?
Have you used MW's native import/export features to create redirects? (while it is fairly easy to generate all your redirects and categories this way, I've seen some erratic behavior on older versions of MW where imported redirects are concerned)