Smart folders bug?

or I'm doing something stupid. I'm on 10.8.2, 2011 Macbook Air.

If I open Finder start doing a search on 'This Mac' with the word epub, "Electronic publication (ePub)" comes up under Kinds in the autocomplete. I select that, and it shows me all the *.epub on my mac.

When I then click the Save button under the Search textbox, I get an option to name it - something like ePub.savedSearch, add to sidebar etc. But then when I go to the saved search, nothing appears. 0 items.

If I right click the saved search and view the criteria, it has "Electronic publication (ePub)" as the Kind. If I change that to straight "epub" and save it then works.