schema mismatch warning

schema modules gives a mismatch warning:

column cid - difference on: not null
declared: array('description' => 'TODO: please describe this field!', 'type' => 'serial', 'unsigned' => TRUE, 'not null' => FALSE)
actual: array('description' => 'The primary identifier for a metatag configuration set.', 'type' => 'serial', 'unsigned' => TRUE, 'not null' => TRUE)