Firefox and Chrome load resources with max-age differently?

I’m trying to troubleshoot something on the client and I believe it has something to do with the the browser caching requests.

I’m loading the same page on Firefox and Chrome (Canary). When I look in the network tab, I see different behavior.

There server response has a max-age set for cache control. I see that Chrome always loads from (disk cache) if max-age has not been reached. But for Firefox, I’ll see it load the resource not from cache once in a while before max-age has been reached. Also I’m seeing 304 ‘not modified’ in Firefox, but not in Chrome.

Can someone help explain what I’m seeing?

Here are some screenshots of the Network tabs… Firefox network tab Chrome network tab