I answered to my two of my own questions on http://meta.drupal.stackexchange.com, and in both the cases the CAPTCHA appeared. I was not editing the same answer twice in row; I was answering two different questions with a CW answer, and passed 4 minutes between an answer and the other, as I was looking for any questions without an answer, to avoid Community would bump the questions. I am a moderator on Drupal Answers, and the questions to which I added an answer are both listed in The 7 Essential Meta Questions of Every Beta.
After 19 minutes (see my activity on meta.drupal.SE), I then added a second answer to the question asked by another user (on the same meta site), and also in that case the CAPTCHA appeared.
I also edited one of the previous answers I gave (just few minutes ago), and the CAPTCHA was not shown.
Is this normal?