#!/usr/bin/perl

use strict;
use warnings;
use feature qw/say/;

my @retCodes_values;

while (<DATA>) {
    next unless /retCode\=/;
    chomp;

    my ($string, $exit_code) = split /retCode\=/, $_, 2;
    push @retCodes_values, [ $string, $exit_code ];
}

if(grep { $_->[1] == 3 } @retCodes_values) {
    say "retCode=3 occurred!"
}

__DATA__
15288 :: Mon Mar 2 13:23:32 2015::App.pm:status returned with retCode=1
15288 :: Mon Mar 2 13:24:32 2015::App.pm:status returned with retCode=3
15288 :: Mon Mar 2 13:25:32 2015::App.pm:status returned with retCode=4
15288 :: Mon Mar 2 13:23:32 2015::App.pm:status returned with retCode=5