TinyMCE is temporarily altering stored content

With WYSIWYG not set to activate any editor, enter the following text into the body of a node:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce dolor. Sed eleifend rhoncus velit. Sed pellentesque turpis sed enim. Sed vulputate ultrices magna. Mauris ut pede. Vivamus sem urna, auctor nec, varius sed, porta aliquet, velit. Sed tincidunt quam id est. Nunc enim massa, ultrices sit amet, pharetra eu, egestas vitae, est. Fusce massa. Donec pretium tellus eget nunc. Quisque diam libero, vulputate sed, accumsan ac, tempus ut, quam. Cras posuere elementum urna. Sed facilisis nunc in diam.

Nullam malesuada, ligula vitae viverra mollis, nunc metus rutrum urna, eu elementum orci sem ut libero. Duis blandit velit ut arcu auctor scelerisque. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Proin convallis tellus ut pede. Nulla ac diam vitae ipsum adipiscing mollis. In eget justo vitae eros consequat porta. Phasellus fringilla ultricies tellus. Cras lorem dui, porttitor in, vestibulum a, ullamcorper cursus, tortor. Donec commodo mi. Etiam neque massa, imperdiet quis, gravida eu, gravida vel, sapien. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur fringilla diam dictum quam. Ut magna.

Leave it as Filtered HTML. Save it.

Then enable the WYSIWYG editor for TinyMCE for Filtered HTML. Edit the node you just created. You'll see that all the paragraphs have been munged together as per http://drupal.org/node/352702, and <p> tags have been added if you look at TinyMCE's code view.

Now without closing that window, in a different window/tab, disable the TinyMCE editor again. In the first window, with TinyMCE still open, do a browser refresh. You'll notice that while the CRLF spacing has been restored,

tags are still present at the very beginning and end of the body content.

This does not appear to be a permanent change. If you then click on the Edit link, the <p> tags disappear.