Wrong datatype of second argument in multistep_is_complete() (line762 of multistep.module)

I get the following warning message when a rule checks if the content of a multistep form is complete:

Warning: in_array() [function.in-array]: Wrong datatype for second argument in multistep_is_complete() (line 762 of /home/mysite/public_html/sites/all/modules/multistep/multistep.module).

Can someone confirm this is a bug? line 732 is: return !in_array('unsubmitted', $status).
The function:

/**
 * Check to see if the node is complete.
 */
function multistep_is_complete($node) {
  // Get the status of all the steps in the node
  $status = _multistep_get_status($node->nid);
  // Look for a step that is not yet submitted
  return !in_array('unsubmitted', $status);
}