flask_mail I get TWO different FROM lines mail header

I'm using flask_mail configured to use gmail smtp server. It sends mail fine except all mail looks it is coming from the gmail smtp user name and NOT from what I set in the 'sender' argument of the mail.send_message(...) command. When I look at the source of the generate emails I see 2 different FROM addresses. How can I change this to show my desired 'from'?

    mail.send_message(subject='subject line',
                      sender='my_from_email@gmail.com', 
                      recipients=['my_to_email@gmail.com'],
                      bcc=['bcc_email@gmail.com'],
                      reply_to='my_from_email@gmail.com')

snip-it of header looks like...

...
From: my_smtp_user_name@gmail.com
X-Google-Original-From: my_from_email@gmail.com
Content-Type: multipart/mixed; boundary="===============8405132704319078372=="
MIME-Version: 1.0
...