If there is an age related algorithm, it can be the case because my previous account was set up in July 2006. But checking the historical graphs on performance reports, I couldn't see any tendency.
IanPC, sorry if I didn't explain it on my first message. The problems I had with the account were that I was using Santander Brazil but it charges a quite high fee for international transfers. And also I have to go in person to my branch in order to approve the charge and confirm the deposit. And since I'm living in the UK and also that ADSense doesn't allow updating the country, I had to create another one.