Thank you for the response, though I am a little confused by the solution.

The $exception needs to be run through the EcomImportUtilities::ageCheck when the program is run, and only not when the "load old" argument is set. Why would I want that to be nested in an "if" statement? My understanding is by declaring $exception = EcomImportUtilities::ageCheck, it actually runs the subroutine. Am I mistaken? Maybe something like this instead:

 unless ($biuw->{const}{load_old}) {
    my $exception = EcomImportUtilities::ageCheck(
            biuw      => $biuw,
            feedpath  => $feedfullpath,
            tablename => $TABLE
        )
    if ($exception->{exception} eq 'outofdate' ||
            $exception->{exception} eq 'stillcopying
        ) {
            $biuw->{log}->warn(
                "$feedfullpath is out of date. " .
                "Loading stopped.\n");    
            return $exception;
        } 
    elsif ($exception->{exception} eq 'nonexistent') {
            $biuw->{log}->warn(
                "$feedfullpath does not exist. " .
                "Loading stopped.\n");
            return $exception;
        }
}
[download]

I think I understand why I am getting the undefined warning now, and I appreciate your help.