If I make a post, hit submit, then realise I've got a typo or something, I'll edit it straight away. Once edited I hit submit and more often than not ('cos I do it fairly quickly) I get a "You cannot make a post so soon after your last post" error.
I'm essentially still working on my last post though. Not a big deal, as I just keep trying to submit until the delay expires but it's a little annoying.