Today I have identified a possible bug in Cloudflare system. When cf-cache-status is Hit. Some of the static cache resources saying * It appears that the Date header has been changed by an intermediary. and it has an age header present. which is causing resources to become stale immediately.
According to this page if an intermediary (cdn) is changing date it should omit Age header. - http://www.cohenwang.com/edith/Papers/HTML/usits01/index.html
I tried reporting the issue using support - #709495 but it seems Cloudflare support staff is not able to understand the issue.