Business::Hours script not returning correct time

RT Users
1

The following code using perl module Business::Hours should return 4 business hours from the date specified in $curtime and update the due date.
For some reason it does that minus the minutes left in the current hour, for example
Ticket created Sun Aug 16 16:17:30 2009 is set due at Mon Aug 17 11:17:30 2009 instead of Mon Aug 17 12:00:00 2009
I have been over the code, faq module docs etc. and cannot spot the error. Has anyone else encountered this?

my $duedate = RT::Date->new($RT::SystemUser);
my $hoursuntildue = 4;
use Business::Hours;
my $hours = Business::Hours->new();

$hours->business_hours(

    0 => { Name     => 'Monday',
           Start    => '08:00',
           End      => '17:00' },
    1 => { Name     => 'Tuesday',
           Start    => '08:00',
           End      => '17:00' },
    2 => { Name     => 'Wednesday',
           Start    => '08:00',
           End      => '17:00' },
    3 => { Name     => 'Thursday',
           Start    => '08:00',
           End      => '17:00' },
    4 => { Name     => 'Friday',
           Start    => '08:00',
           End      => '17:00' },

    holidays => [qw(01-01 12-25 07-04)],
);

my $curtime = time;
my $bus_hours_duetime = $hours->add_seconds ($curtime, ($hoursuntildue6060));
$duedate->Set(Format=>‘unix’, Value=>$bus_hours_duetime);
$self->TicketObj->SetDue($duedate->ISO);
return(1);