Too many comments? Que pasa¿

This evening while perusing DJ, I offered some comments on some articles, so far so good. However, at one point, and in response to a comment, instead of the comment posting to the article, I received a pop-up box: We noticed you're posting quite a few comments in a short period of time. Please wait a few minutes before commenting again. I've made a few comments from time to time here, and never seen that box before. My question is: Is that a new restriction which has been put in place or simply an aberration in the commenting process which I've run afoul of?