I would email google and let them know you're having "unusual activity" on your account... Just in case...
Do not email! Go to the adsense help and fill out one of the forms for help. They answer quickly and will take care of the problems. Reporting by email may get delayed or ignored. https://www.google.com/adsense/support/bin/request.py?
Just watch for one more day and if it is continuing check your server logs for same ip adress visits and clicks, if it so then report, else enjoy the traffic and clicks