It's the rate-limiting kicking it when an account sends too many requests in a short amount of time. Or you're trying to submit from a page that has been opened for too long and the token expired.
Gotcha, thanks. I opened a bunch of tabs for different threads I wanted to read, and then tried to comment.
That's your issue then.
When it happens you must wait a few minutes.
This measure is to prevent spambots and flood abuse.
I understand why rate-limiting would be used. I'm not complaining. Thanks for the clarification.
(post is archived)