Identify gaps in logs (DateTime, broken version)

gistfile1.pl

#!/usr/bin/perl
use strict;
use warnings;
use autodie ':io';
use DateTime::Format::Human::Duration;
use DateTime::Format::Strptime;

my $min_gap = shift || 3600;
my $span = DateTime::Format::Human::Duration->new;
my $dtparse = DateTime::Format::Strptime->new(
    pattern   => '%F %T %Z',
    locale    => 'en_GB',
    time_zone => 'Europe/London',
);

my $prev;
while (my $line = <>) {
    my $ts = parse_date($line);
    if ($ts) {
        if ($prev) {
            my $delta = $ts - $prev;
            if ($delta->in_units('seconds') >= $min_gap) {
                print "--- GAP: " . $span->format_duration_between($prev, $ts) . " ---\n";
            }
        }
        $prev = $ts;
    }
    print $line;
}

sub parse_date {
    my $line = shift;
    $line =~ /^\[ (.*?) \]/x or return;
    my $ts = $dtparse->parse_datetime($1);
    return $ts;
}