For extended periods? I am not sure if we can discuss this but I have three sites that have over 35% CTR this month... should I be concerned?
I don't think so - I have a few like that, that have been there for yonks with up to 45% at times on one of them - it is actually a serious site but it is the nature of the business that people are just browsing like a magazine, so I guess one should expect it.
It happens sometimes in a few days time...Not months. If you have nice traffic and nice content why should you worry? Are you doing anything wrong?