Plaintext Message sent /w MimeMail off works, but when on send message body to 'Array'

Anyone come across this one?

Using drupal_mail and hook_mail, the plaintext message sent /w MimeMail off works fine but when Mimemail is on, the body of the message received is just the text Array.

function example_mail()
{
      $body = 'testing 123';
      $message['subject'] = 'test subject works';
      $message['body'][] = 'some sample text here';  // always shows in received email as: Array
}

Have another email w/ HTML sends correctly, the above message is just a simple plain-text test and will not work.

Is this normal? It looks like a bug, if I set at admin/config/system/mailsystem to DefaultMail the plain-text ones sends correctly and the html-text version also sends, but is all mashed up, non-html, as expected. When set admin/config/system/mailsystem to MimeMailSystem, only the HTML $message['body][] = get_html_text(); works, and the plaintext email received just has the word 'Array' in the body of the email.

Anyone MimeMail experts seen this behavior? Common? Know a fix?

Thank you!