For some reason QA nodes have an author_user of "QandAEditors" instead of the handle of the person who actually posted. This is dealt with differently on different pages, which leads to the inconsistancies that you've noticed.
The XML interface can help you verify this: View the source on this query to see the data for a normal node posted by you. Notice that you are the author_user. Compare that to the info for a Q&A post where the author_user is "QandAEditors" instead of an actual username.