I've only experienced this when I post on my iPod, but sometimes when I post something the entire message is erased and instead appears as if I've only posted a full stop. When I try to edit the post with an actual message it still doesn't change. I'm pretty sure I've seen this happen to others as well, so I don't know if this has been reported already because I tried searching.
Is there some kind of limit to how much you can post in one day or something, or is this a bug?