[squid-users] Clock sync accuracy importance?

I'm trying to run a squid accelerator on a server in India, accelerating
an origin host in the USA. I don't have a ton of experience with ntpd
but I think I have it running properly on both sites. For whatever
reason, they are always 20 seconds out of sync. Squid is not appearing
to cache items on the India server. It's always contacting the origin
server on every request, and I assume this is because of the clock
discrepancy.

Is there any way to tell squid that a minute or two drift in either
direction is OK?

Also, is there any way to find out exactly what decisions squid is
making so I can tell for sure if it's the clock issue or something else?
  Maybe my headers aren't correct?

HTTP/1.1 200 OK
Date: Tue, 15 Apr 2008 17:32:23 GMT
Server: Apache/2.0.61 (Unix) PHP/4.4.7 mod_ssl/2.0.61 OpenSSL/0.9.7e
mod_fastcgi/2.4.2 DAV/2 SVN/1.4.2
X-Powered-By: PHP/5.2.3
Cache-Control: max-age=300, stale-while-revalidate, stale-on-error
Vary: Accept-Encoding
Content-Type: text/html

Should I throw an Expires header in there?

-jsd-
Received on Tue Apr 22 2008 - 14:14:50 MDT