Comment # 3 on bug 975364 from Wolfgang Bauer

(In reply to Per Jessen from comment #2)
> Maybe something we should do whenever Plasma is
> upgraded?

Sorry, but no. That's rather impossible.
Packages are installed as root, it's not really feasible (nor acceptable IMHO)
to change users' files.

That said, Plasma should detect when the theme files are upgraded and recreate
the cache.
And that works fine here AFAICT.

There was a problem with this in earlier versions (the themes' versions were
not updated so Plasma didn't notice the change), but that should be fixed in
the latest versions.

If you can (reliably) reproduce it, it would be a good idea to report it
upstream at http://bugs.kde.org/ though.
It might be a special problem with nfs...