Error: 'cannot modify header information' after updating via Editor

I have the following error after updating any of my php pages using the editor, any clues how to rememdy?

Warning: Cannot modify header information – headers already sent by (output started at /home6/paulprud/public_html/paulprudence/wp-content/plugins/twitter-tweet-button/inc/main_class.php:54) in /home6/paulprud/public_html/paulprudence/wp-admin/theme-editor.php on line 69

Thanks in advance,
paul