I don't think that is luck. If the average CPC is high enough you can earn that per click. I once got a $24 click. It is seriously possible.
This is great.....so If you are using the tracking channels in AdSense then you will know in what Page got this click and the content that advertising. So you can write content similar to it and bring high cost CPC for your clicks.
1) I use custom channels and Separate AdUnits. Say Top banner has different channels and postbit has separate channels. I use different leatherboard with link only, Link+text+image, image only. 2) Basically I use about 9 different ad units to suite different pages of mine. At the end of the day I click on "reports" and click on adUnits. Even if there are 1000 clicks on that day, one unit will show unusually high CPC. Then I track those channels that I am using for that Ad unit. There are only five channels allowed par adUnit, it is never difficult to know that invariably such high CPC comes from link ad and either first or second link. I guess that clears your doubt , of how to track the type of Ads which fetches you good revenue.
Congratulation for getting such a big click on your ads. Which niche you are using? Do not be worry about your CPC. It is not a big deal where your visitor is from USA.
I wonder what your niche is. If its finance, then I wouldn't be surprised. It means that you're making good progress. Analyze the data and find out what articles gave you those clicks and find out more related keywords based on them, write more articles on them. May be you'll get more of the same thing. 2 cents.
There are a few times on Adsense wherein companies pay ridiculous prices for certain keywords pertaining to to their ad, but keep in mind this happens quite rarely.