I've been noticing something different in Twitter's behavior recently when following protected users.
If I send a friendship request via API, it returns the user profile like it was successful. But the outgoing ids don't update nor am I now following the person. I also don't see the old error that you already requested to follow this person anymore. I'm also seeing this behavior via web. Clicking send request does nothing and doesn't show that I sent a request to follow when it finishes or I refresh. Is there something obvious I'm missing here or is this just an intermittent problem?