Yesterday was my lowest day in 3 months. today is back to normal somewhat but 7 clicks on 4 impressions for 1 site and no advertising just some dir link building. then 1 hour later 6 clicks on another site which helped a lot but I feel they are invalid clicks. but I did market this site today on heavy traffic site so it could be true. bottomline: if I think it is unusual, Google will too. Can someone get you canxed from adsense
If you notice some very unusual click activity, such as click bombing, your best bet is to email google adsense and let them know your concerns. This can help protect your account. You can also try to find the IP from where the clicks are coming and block it as well, if you are concerned it's a competitor trying to get you banned.
Don't email them with a puny 4 impressions, it's a waste of their time. They will 99.9% chance ignore this incident unless you clicked them yourself.
What I have read from various AdSense FAQ, you don't have to be alarmed if this is a one or two times issue. But if you are getting strange clicks continuously everyday, you should be alarmed and let adsense team know. Even if they do not reply soon, it's more like an insurance. If they actually find the problem later and warning you, you can submit the email as a proof that you were trying to report the problem.
IMO Just observe the clicks for another day or two, if you are continuously getting large amounts of clicks from the same ip address then ban that ip address and inform the Google officials.