Occasionally, when I search for text on a page I won't find what I'm looking for because I left "Match Case" selected from an earlier search. It might be helpful if the Find bar showed a slightly different "Phrase not found" message when a case-insensitive search was performed and no results were found. e.g. "Phrase not found (Match Case is selected)"
Bug 384883 suggests changing the background color of search input field which might make a nice supplement to this bug about adding a case-sensitive hint to the "Phrase not found" feedback msg.
It'd be super funny if it would display 'pHrASe NoT fOuND' when 'Match Case' is selected.