Hi all!
The search data for some of the forums, including Evolution, had lost some search data, so today I updated the the search database for all forums. All search data for all forums is now up to date.
Generally, you can trust the results of searches - if the search engine can't find it then it isn't there. But occasional glitches on the server, usually due to process overload, sometimes results in the loss of data. I'll try to rebuild the search database whenever I notice this has happened.
Note to other admins - if you have control panel privileges, there's an "Update Search Database" link in the navigation bar. When you notice that the search data is out-of-date feel free to use this. It takes about 15 minutes, but you don't have to watch it work.
--Percy