Twitter/Summize search flaky?

I’ve started to post more on my twitter account recently. Less than two weeks ago, Twitter bought Summize. Good for them; I like both companies. But http://search.twitter.com/search?q=wordpress+mattcutts should return this entry in Twitter’s search results. I don’t see it in Twitter’s search results:

What’s the story, Twitter/Summize folks? I can’t escape the feeling that I would have found that entry on pre-acquisition Summize. Does anyone know more about when Twitter’s search has gaps?