I and many others have noticed numerous issues with regards to the WYSIWIG, as have people who have access to submit bugs to WordPress Trac (http://trac.wordpress.org/)
This ticket (http://trac.wordpress.org/ticket/6485) concerns me because it reports exactly what is making all us end-users lives hell, and it doesn't seem like the problem is actually getting to the point where it can be reviewed. The person who closed the bug said there is not enough information to duplicate.
Well here is that information:
1. after disbling WYSIWIG, copy this code: <form><label>first name<input type="text"><input type="submit"></form>, into any page
3. view page/source to see what WP does to it