Let's attack this slightly differently:

# get date 90 days ago
my ($start_d, $start_m, $start_y)
  = (localtime(time - 90 * 86_400))[3,4,5];

my $start = sprintf('%4d-%02d-%02d', $start_y+1900, 
                                     $start_m+1,
                                     $start_d);

foreach (<FILE>) {
  my ($y, $m, $d) = (split /,/)[28,29,30];

  my $date = sprintf('%4d-%02d-%02d', $y+1900, $m+1, $d);

  if ($start gt $date) {
    # record is more than 90 days old
  } else {
    # record is within 90 days
  }
}
[download]

Update: buckaduck has caught me writing code before drinking coffee. And didn't even point out the worst problems with the code. The new version is (hopefully) better.

Update2: ergh! I give up. This time I was using numeric comparisons instead of string comparisons.

--
<http://www.dave.org.uk>

"The first rule of Perl club is you don't talk about Perl club."