[Greasemonkey] Changing existing Javascript code

[Andrew Ducker]

I have a script here:
http://www.notzen.com/andrew/LiveJournalBlockQuote.user.js

You can test if by going here:
http://andrewducker.livejournal.com/1031325.html?mode=reply

Select some text, and hit the Quote button.  If there's a newline then 
it uses <blockquote>, if not it uses <q>.

My script _should_ be changing this behaviour to use "blockquote" all 
the time.

It doesn't work.

Now, it's definitely doing the right replace - if you check the log 
afterwards, the page has been changed to have the replaced code. 
However, the actual running code seems to be the version _before_ my change.

Does Firefox cache any javascript code in a page, making it impossible 
to change it?  Or am I missing something obvious?

Cheers,

Andy D