The code you are using is specifically for the month abbreviation, (Oct). You should be using this:
function eventposttype_get_the_month($month) {
global $wp_locale;
for ( $i = 1; $i < 13; $i = $i +1 ) {
if ( $i == $month )
$month =$wp_locale->get_month( $i ) ;
}
return $monthabbr;
}