If the browser displays its own cached version of the page you will not see the
headers sent to WWWOFFLE. This is because the browser does not make a request
but is just using the copy of the page that it has already got cached. There is
no way to force a browser re-fetch this URL from WWWOFFLE, it is purely the
browser's decision.
If you have this problem then the only solution is to force the browser to
reload the URL when this link is followed. This can be done by forcing the
browser to clear its cache.