See the attached image. I saw this today in one of my accounts. I certainly can't be too disappointed with that CTR.
Yeah it's happened to a bunch of my keywords usually right when you turn them on of if you are looking at the stats really soon after it's going for that day and I've spoke with Google about it and they said this happens because clicks may be updated sooner than impressions for your keywords so it is usually best when checking your stats to look at the day before so it has time to give you all the data.
Try beating getting a lead/sale without a (paid) click Got it a couple of times, and I sometime think that the Googlebot randomly fills in info in the CPA offer. Not that I'm complaining!
That always happens. It's because clicks are updated approximately every hour, while impressions can take up to three hours to be updated. Consequently, there have been times where I've had CTRs of up to 300% for particular keywords!