It appeared to me that Q simply corrected the Anon and told him he was wrong and gave him the correct delta of 5 minutes.
Maybe if Q could not find a correct Anon decode of the post regarding McCabe, then Q was forced to use an incorrect Anon post.
Didn't see any intent to use an Anon error as part of Q comms. That way lies insanity. We can never make our own errors whether they be typos or computing to be a part of trying to understand Q.
Q corrected the Anon. And pointed other deltas missed.