Portsnap snapshot date in past abort

[Darren Spruell]

Receiving this recently:

Looking up portsnap.FreeBSD.org mirrors... 3 mirrors found.
Fetching snapshot tag from portsnap1.FreeBSD.org... done.
Latest snapshot on server is older than what we already have!
Cowardly refusing to downgrade from Sun Mar 28 01:00:58 MST 2010
to Sat Mar 27 01:20:17 MST 2010.

I recall in other systems' package management repository update
schemes seeing similar metadata errors and I've always felt it may be
due to the caching on a transparent HTTP proxy on the network egress.
Is the above likely due to such a situation? If so, is there a
canonical "fix" for the issue (configuring cacheability on mirrors,
configuration/tuning on proxies, options that may be passed on client
side to signal bypass of cache?

Or am I completely off base on this one?

FreeBSD 8.0-RELEASE-p2 FreeBSD 8.0-RELEASE-p2 #0: Tue Jan  5 21:11:58
UTC 2010     root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC
 amd64

# /etc/portsnap.conf
SERVERNAME=portsnap.FreeBSD.org
KEYPRINT=9b5feee6d69f170e3dd0a2c8e469ddbd64f13f978f2f3aede40c98633216c330
INDEX INDEX-6 DESCRIBE.6
INDEX INDEX-7 DESCRIBE.7
INDEX INDEX-8 DESCRIBE.8

-- 
Darren Spruell
phatbuckett at gmail.com