Issue: TOC Book Flag Breaks on Post Cache

I've been playing with the wiki on my site today, been customising the css etc and noticed some things with the TOC book command, this is what is basically happening.

I have a book created with 3 chapters, at the top of each article/chapter I added the [ toc ] book [ /toc ] commands which worked fine, it showed the 3 chapters with all the sub headings below each chapter that I created, I navigated through these fine.

Now when I go to a page direct (instead of through the book index) the book contents are gone and have been replaced with the normal TOC, If I click on Index it will still take me to the main index page but if i then follow the table of contents back to the article the nice book toc is still gone.

The only way to view the book with the Book TOC is to edit and save the page again. It does this in Firefox and IE. Once I've visited a page direct and not through the book contents, the Book TOC has been replaced with the default TOC.

hope this makes sense......easier to just go and click on a few links and you'll see what I mean