:: wondering how much longer this can go on before phranque puts his foot down and starts chopping ::
this response is "stock-standard" for an HTML extension rewritten to PHP:
The quoted response is identical to what Live Headers gives me when I try the same request in MAMP. (Right down to php version: You didn't get it from your own MAMP did you?) That's for any request, whether html physical file or html rewritten to php.
I'd assumed the "cache-control" and "expired" lines were because I have explicit caching times set in htaccess, and the numbers match. But I have the same lines in my local file's htaccess, and the headers are absent.