#!perl! -w
use strict;
use WWW::Mechanize;    #browser, extends LWP
use HTTP::Cookies::Mozilla;    #cookie reader for bot

my $mech = WWW::Mechanize->new();
$mech->cookie_jar(HTTP::Cookies::Mozilla->new(
        file => 'cookies.txt',
        autosave => 1
)) || die "Couldn't fill cookie jar!\n";
my $url = "http://www.insor.org/insasoweb/offenderDetails.do?sid=35465
+6.011";
$mech->get($url);
print $mech->content;
[download]

You will notice the difference between how the page looks in the browser and what prints, I hope.

See, now that you've given a concrete example to look at you can easily see that the page in question (after you accept their disclaimer thing and get back a session cookie . . .) has the full date text. The page contains a call to pull in a JavaScript file "common.js". Said "common.js" contains a function formatDate which looks to munge dates.

Given this it's not out of the realm of possibility that there's something calling javascript and munging all the dates. This easily explains the difference between what you see in your browser (even if you view source, you're seeing the source after it's been walked over) and what Mechanize is showing. You can easily confirm this by comparing the output from a third party (say curl and using the JSESSIONID cookie value pulled from your browser) which should match what Mechanize says it is.

The cake is a lie.
The cake is a lie.
The cake is a lie.

Thanks, I'm impressed. I had never noticed you can look inside the js source code before. I'm still confused about how Mechanize would be getting the munged date but a normal browser wouldn't, but regardless, the solution lies in the formatting.