Apply easy micro-optimization.

src/Response/Status.php

@@ -65,11 +65,11 @@ class Status implements ResponseInterface
         switch ($payload) {
             case 'OK':
             case 'QUEUED':
-                if (!isset(self::$$payload)) {
-                    self::$$payload = new self($payload);
+                if (isset(self::$$payload)) {
+                    return self::$$payload;
                 }
 
-                return self::$$payload;
+                return self::$$payload = new self($payload);
 
             default:
                 return new self($payload);