I've experienced the same problems. I couldn't find that old post of mine about the chickens. When I simply browsed through pages and pages of old posts of mine, I finally found it. It contained the exact search phrases I had tried.
This is definitely a bug, and not a misunderstanding on your part.
Here it is. I had to look for it again, because I am rather rigorous about clearing out my browsing history. In the end I had to resort to google, can you imagine?