I don't think an e-mail is even necessary... once is an accident... it shouldn't affect you... they will though ban you if they notice you do it in a regular basis.... or something
what is necessary is that you don't bump up threads that are dated 2005. anyway i think the title is funny.
OMG, it IS from 2005. How hilarious. Yes, I think you should email Google Support and tell them you clicked on your ad in 2005.
I saw that google adsense has emailed someone/some people and said that they do notice when people click their ads every once and a while. They basically said they have been getting tons of emails, and said it was alright to accidentally click your ad every once and a while, and not have to email them about it. I think they might have said something about you can click your own ads, only if you are truly interested in what you are clicking, and not just clicking for fraud. I am not sure on that last part though. Good luck!