TCP_MISS/304 is a bit different; what this means is that it isn't
in the Squid cache, but it is in your browser's cache. Your browser will
submit a If-Modified-Since request to Squid, which will forward it on to the
origin server. If the object hasn't been modified, it'll get a 304, which
Squid will pass on to your browser. However, Squid doesn't have a copy
itself, therefore TCP_MISS.