I agree with buckworks,
I've seen this happen too many times with Google to raise any panic flags. You may end up with a slow Google month so go out and find a great link that will compensate for the traffic. That's what I did when I had an odd Google month and that link has more than compensated, even when Google popped back in the following month.
This isn't a reflection on you but, people freak out way to quickly when Google has it's moment. Most, not all of us, deal with it at one time or another. There are just too many 'things' it could be to even determine sometimes what it is and then when you blink, it all changes again.