I'm not trying to be pedantic about, but I'd be surprised if it were the DNS causing the problem. Here's why:

4:05am - I posted -- post showed up correctly on the thread
4:07am - I posted again to the same thread -- post missing
4:10am - I posted again to the same thread -- post showed up correctly

Because it's nested between two successful posts, we were obviously using the updated DNS entry -- there'd be no reason for it to revert to the old DNS entry for five minutes, then switch back again, would there?