For the sake of consistency, I'd say it should probably be:

```php
   if (!$this->isConnected()) {
        $this->connect();
    }
```

`connect()` checks if `$this->resource` is set and returns early anyway, but [everywhere else](https://github.com/zendframework/zf2/blob/e00aefc81ca7309599b9b26aa51795c4440f74a7/library/Zend/Db/Adapter/Driver/Pdo/Connection.php#L145-L147) `connect()` is called lazily, it's wrapped in a conditional, so we should at least keep it consistent. :)