Gmail Spam Filter

Gmail used to have the best spam filter ever: I would never get spam in my inbox. In fact, until a few weeks ago I would have been unable to say when was the last time I had pressed the Report Spam button. Unfortunately, over the past few weeks, I've been clicking on that button more and more, the last time being 5 minutes ago. I only get a few a day at the moment but the worrying thing is that they are all email that look like they should be blocked by the most brain dead of spam filters. Is something broken in the Googleplex? In their relentless attempts at blocking the more devious spam messages, did they accidentally break something in the code that was blocking the simple ones?