Description:
------------
When using mktime and the date functions it seems that instead of properly returning "February" the two functions used together will return "March"

Reproduce code:
---------------
<?php
$i = 1;
do {
  
  echo "date(\"F\", mktime(0, 0, 0, $i)); --> ".date("F", mktime(0, 0, 0, $i))."<br />\n";
  $i++;
  
} while ($i < 13);
?>

Expected result:
----------------
date("F", mktime(0, 0, 0, 1)); --> January
date("F", mktime(0, 0, 0, 2)); --> February
date("F", mktime(0, 0, 0, 3)); --> March
date("F", mktime(0, 0, 0, 4)); --> April
date("F", mktime(0, 0, 0, 5)); --> May
date("F", mktime(0, 0, 0, 6)); --> June
date("F", mktime(0, 0, 0, 7)); --> July
date("F", mktime(0, 0, 0, 8)); --> August
date("F", mktime(0, 0, 0, 9)); --> September
date("F", mktime(0, 0, 0, 10)); --> October
date("F", mktime(0, 0, 0, 11)); --> November
date("F", mktime(0, 0, 0, 12)); --> December

Actual result:
--------------
date("F", mktime(0, 0, 0, 1)); --> January
date("F", mktime(0, 0, 0, 2)); --> March
date("F", mktime(0, 0, 0, 3)); --> March
date("F", mktime(0, 0, 0, 4)); --> April
date("F", mktime(0, 0, 0, 5)); --> May
date("F", mktime(0, 0, 0, 6)); --> June
date("F", mktime(0, 0, 0, 7)); --> July
date("F", mktime(0, 0, 0, 8)); --> August
date("F", mktime(0, 0, 0, 9)); --> September
date("F", mktime(0, 0, 0, 10)); --> October
date("F", mktime(0, 0, 0, 11)); --> November
date("F", mktime(0, 0, 0, 12)); --> December