Preview doesn't show the user submitted "Author is " text

Issue Summary

I've got a content type with enabled authorship module.

When users (authorized to use authorship module) write some of this content type, and write anything else other than the default at the "Authored by" field, the preview button still displays their real user id, even though after submitting the content the "Authored by" field is no longer the user id but the user submitted text.

This might mislead users into think that if they submit the content their user id will be displayed instead of the user submitted text, thus preventing them to take profit of the anonymicity this module affords.

Thanks,

Guillem.