I did find some more hints here, I modified them slightly. This one finds a single file older than 20 minutes and prints a message to stdout:

#!/bin/perl -w
use strict;
my $mytime=(time);
my ($File,$FileStat,$CallOutDir);
chdir 'C:/devl/bin' or die "Arghh!!! $!";
opendir(ROOT, ".") or die "Arghh!!! $!";
foreach $File (readdir(ROOT)) {
    next if $File=~/^\./;
    if ($FileStat = (stat $File)[9]){
        if ($FileStat <= ($mytime - 1200)) {
        print "File older than 20min found. The file name is $File";
        #send mail here....
        last;
        }
    }
}
[download]

I'd like it to list all files older than nnn minutes, and I will have to figure out how to make this spit out a file rather than a msg. to stdout.