not sure about what pissed the OP off though. I often get this 30 sec notification and it usually means that your post has already been made. it just prevents you to post the same thing twice
if you post the identical post in the same thread twice within 5 mins it tells you: "that's the same post you made in the last 5 mins. Do you really wanna post it?"
but the 30sec notification means you have to wait till you are "unblocked" for posting again. The post isn't done then.