False negative? - FAILED (No max-age or expires)

[sajal]

Ive been playing with webpagetest for last few weeks, but from last 2 - 3 days i have a strange issue.

The result in discussion is at http://www.webpagetest.org/result/100609...9331716a5/

In the first view, these requests(served via Internap CDB) are listed as cachable while in the repeat they arent.

http://i.ticdn.com/header_bg.gif
http://i.ticdn.com/menu_bg.gif
http://i.ticdn.com/side_bg.gif
http://i.ticdn.com/tab_bg.gif

Firefox 3.6.6pre does not check for these files for each view (checked wia firebug). Neither does IE6 (monitored activity via wireshark) ...

I havent tested this in IE7 or 8 yet .

I think the only change i did was to add "Vary: Accept-Encoding" header so that only gzip compatible browsers get gziped content...

FYI here are the headers for http://i.ticdn.com/header_bg.gif

Code:

HTTP/1.0 200 OK
Date: Wed, 09 Jun 2010 13:00:54 GMT
Expires: Mon, 19 Jul 2010 13:00:54 GMT
Server: nginx/0.7.65
Content-Type: image/gif
Content-Length: 6133
Last-Modified: Sun, 05 Nov 2006 06:25:24 GMT
Cache-Control: max-age=3456000
Vary: Accept-Encoding
Cache-Control: max-age=3456000, public
Accept-Ranges: bytes
X-Origin-Date: Tue, 08 Jun 2010 14:45:49 GMT
X-Origin-Expires: Sun, 18 Jul 2010 14:45:49 GMT
X-Cache-Age: 78637
X-Cache: HIT from cdce-nym011-015.nym011.internap.com
X-Origin-Date: Wed, 09 Jun 2010 12:36:26 GMT
X-Origin-Expires: Mon, 19 Jul 2010 12:36:26 GMT
X-Cache-Age: 1468
X-Cache: HIT from cdce-nym011-015.nym011.internap.com
Via: 1.1 cdce-nym011-015.nym011.internap.com:1082 (squid/2.7.STABLE7), 1.0 cdce-nym011-015.nym011.internap.com:80 (squid/2.7.STABLE7)
Connection: keep-alive