Vernis: Cacheble mais pas de mise en cache

si je lance cette commande

varnishtop -i txurl

que la demande est "cacheble", mais pas "en cache". Je vois "Age=0" (âge de la garder dans le vernis), comment le modifier?

C'est la demande de mon .page php

GET-Utilisé http://example.com

User-Agent: lwp-request/5.810

200 OK
Cache-Control: max-age=60, public, must-revalidate
Connection: close
Date: Sat, 18 Feb 2012 12:14:33 GMT
Via: 1.1 varnish
Age: 0
Server: Apache
Vary: Accept-Encoding
Content-Type: text/html
Expires: Sat, 18 Feb 2012 12:24:33 GMT
Client-Date: Sat, 18 Feb 2012 12:14:34 GMT
Client-Peer: 173.236.219.104:80
Client-Response-Num: 1
Client-Transfer-Encoding: chunked
X-Cache: MISS
X-Cacheable: YES
X-Varnish: 840966561

.htaccess code

# BEGIN Expire headers
<ifModule mod_expires.c>
  ExpiresActive On
  ExpiresDefault "access plus 5 seconds"
  ExpiresByType image/x-icon "access plus 2592000 seconds"
  ExpiresByType image/jpeg "access plus 2592000 seconds"
  ExpiresByType image/png "access plus 2592000 seconds"
  ExpiresByType image/gif "access plus 2592000 seconds"
  ExpiresByType application/x-shockwave-flash "access plus 2592000 seconds"
  ExpiresByType text/css "access plus 604800 seconds"
  ExpiresByType text/javascript "access plus 216000 seconds"
  ExpiresByType application/javascript "access plus 216000 seconds"
  ExpiresByType application/x-javascript "access plus 216000 seconds"
  ExpiresByType text/html "access plus 600 seconds"
  ExpiresByType application/xhtml+xml "access plus 600 seconds"
</ifModule>
# END Expire headers

# BEGIN Cache-Control Headers
<ifModule mod_headers.c>
  <filesMatch "\.(ico|jpe?g|png|gif|swf)$">
    Header set Cache-Control "public"
  </filesMatch>
  <filesMatch "\.(css)$">
    Header set Cache-Control "public"
  </filesMatch>
  <filesMatch "\.(js)$">
    Header set Cache-Control "private"
  </filesMatch>
  <filesMatch "\.(x?html?|php)$">
    Header set Cache-Control "public, must-revalidate"
  </filesMatch>
</ifModule>

Par défaut.vlc

backend default {
    .host = "173.236.219.104";
    .port = "81";
     .connect_timeout = 600s;
    .first_byte_timeout = 600s;
    .between_bytes_timeout = 600s;
}

sub vcl_deliver {
        if (obj.hits > 0) {
                set resp.http.X-Cache = "HIT";
        } else {
                set resp.http.X-Cache = "MISS";
        }
}

sub vcl_fetch {

    # Varnish determined the object was not cacheable
    if (beresp.ttl <= 0s) {
        set beresp.http.X-Cacheable = "NO:Not Cacheable";

    # You don't wish to cache content for logged in users
    } elsif (req.http.Cookie ~ "(UserID|_session)") {
        set beresp.http.X-Cacheable = "NO:Got Session";
        return(hit_for_pass);

    # You are respecting the Cache-Control=private header from the backend
    } elsif (beresp.http.Cache-Control ~ "private") {
        set beresp.http.X-Cacheable = "NO:Cache-Control=private";
        return(hit_for_pass);

    # Varnish determined the object was cacheable
    } else {
        set beresp.http.X-Cacheable = "YES";
    }

    # ....

    return(deliver);
}