I've never set a different password for MySQL than for my (own personal) cPanel account, and even after the upgrade to 11.28 on what used to be known as the RELEASE tree, I could always automatically go to PHPMyAdmin from within cPanel. With last night's upgrade to 11.28.87 this is changed.
My cPanel username and password are not working in the PHPMyAdmin login form.
EDIT: And as for the annoying "stock suggestion" of clearing your browser cache... #1, I have cache disabled in my main browser, and #2 I also tried logging in from a browser I have never accessed cPanel from. Same login problem.