What kind of page are you talking about here?

From the description, you seem to be implying that it isn't a login screen or a user settings/configuration/password change page... but what is it exactly?

Personally, and without any knowledge of how things actually work, I would expect that a password change dialog would be needed whenever *TWO* hidden-type fields are seen on the same form. I would expect to have to autofill an existing password whenever there is only a single hidden-type field.