Adsense earnings down last month?

My Adsense earnings took a bit of a hit last month.

I don’t think it has anything to do with Panda or any algorithm changes; my sites still rank the same or better than they have in the past few months, and same amount of visitors, just significantly less clicks (or maybe lower revenue per click… honestly the new AdSense interface keeps giving me errors so I can’t get any detailed stats).

I know there are monthly fluctuations and everything, but last month was a bit outside of these fluctuations, that’s why I asked.

Did this happen to anyone else?