[TYPO3-english] indexed search finds pages that are not indexed. why?

[Martin Mädler]

Hello Typo3 people,

the official documentation for the exension indexed_search (last update 
about 2.5 years ago) states that the search is based on indexing, which 
occurs when someone is visiting a page. In the backend under 
"Info->Indexed Search" I can see which pages are indexed.
http://typo3.org/documentation/document-library/extension-manuals/doc_indexed_search/4.2.1/view/1/3/

However,  the acual search finds pages that are not indexed. I tested 
this by deleting the entire index and subsequently performing a search. 
What is happening here? Is this supposed to happen? Is the index even used?

P.S. I'm running TYPO3 4.5.3 with indexed_search 2.12.0.

Best Regards
Martin Mädler