Drush command needs higher bootstrap level - Pantheon Drush Alias Setup
While sites on Pantheon don't require a settings.php file in order to serve web requests, due to the fact that database credentials are dynamically injected, they will still need a settings.php configuration file present in order to enable the remote execution of Drush commands. With Drush 5 installed locally, there is unexpected behavior with Pantheon aliases run from inside a local Drupal docroot. In addition, the --strict=0 option needs to be appended to most commands when using Drupal 6 on your local dev environment.

Source: Drush error “Could not find a Drupal settings.php file” or missing system information from status