Cloudflare doesn't respect my origin cache control header

[200706991]

Cloudflare doesn’t respect my origin cache control header.

My nginx server return

cache-control: public, max-age=14400, s-maxage=2592000

for every request.
But for html files, it still returns

cf-cache-status: DYNAMIC

for other cachable file extensions, it returns:

cf-cache-status: EXPIRED

I’ve already purge all cache and refresh my browser for several times.
Something wrong with my settings?

[200706991]

My nginx server return

cache-control: public, max-age=14400, s-maxage=2592000

for every request, but I get

cf-cache-status: EXPIRED

for files with cachable extentions.
for any other uri, it returns

cf-cache-status: DYNAMIC

Shouldn’t it respect my cache-control header, as this doc says:

Cloudflare caches the resource in the following scenarios:

• The Cache-Control header is set to public and the max-age is greater than 0.