DateTime.pm and midnight

Why does the following code return 0 minutes instead of 60?

use DateTime;
use DateTime::Duration;

my $year = 1969;
my $month = 4;
my $day = 2;
my $hour = 23;

my $datetime  = new DateTime (year => $year,
                              month => $month,
                              day => $day,
                              hour => $hour);

my $onehour   = new DateTime::Duration (hours => '1');

my $elevenpm  = new DateTime (year => $year,
                              month => $month,
                              day => $day,
                              hour => '23');

my $midnight  = $elevenpm + $onehour;

my $delta = $midnight - $datetime;
print $delta->minutes, "\n";


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