Sound like a server config issue cause pagespeed don´t set headers for this amount of time.
It put 1 year for optimized resources or leave the "original" headers otherwise.
Maybe is an .htacces file in this folder?
And the strnage thing is that are not rewrited by pagespeed.
so files under
/var/www/vhosts/******.com/public_html/ are loaded from disk by pagespeed.
The LoadFrom File has a "
The files are loaded from disk so no http header are set, then pagespeed set a cache-control with the default 300 (5min)
The rest of headers are set not to the original resource but to the pagespeed rewrited one when is served by the web server.
The original cache-control header tell pagespeed how much time the optimized/rewrited resource hold in their cache, so if no original cache-control are set
and the defaul 5min is used, the resource need to be optimized every 5 min.
For solve ths there are 1 directive: