my @d = $ftp->ls();
    for (@d) {
        my $mdtm = strftime("%Y/%m/%d %H:%M:%S", localtime($ftp->mdtm($_)));
        print "filename = $_\nmdtm = $mdtm\n";
        # check file is newer than whatever criteria you have
        if ($mdtm ge "whatever") {
            $ftp->get($_);
        }
    }