Arg. I just tried with my real code running perl 5.8.8, and it does actually a difference : use base 'Exporter' works, use Exporter doesn't (??!?!?). The module is absolutely trivial :

package DBtools;

use strict;
use warnings;

use DBI;
use Exporter;

our @EXPORT=qw( dbconnect );

#sub definition
sub dbconnect {
    my $config = shift;

    my $dbh = DBI->connect(
        'DBI:'
          . $config->param('dbdriver')
          . ':dbname='
          . $config->param('dbname')
          . ';host='
          . $config->param('dbhost'),
        $config->param('dbuser'),
        $config->param('dbpassword'),
        { PrintError => 0, RaiseError => 1, AutoCommit => 0 }
      );

    return ($dbh);
}

1;
[download]

I'm going to stick with "use base" for now :/