Code: 89 Invalid or expired token on valid tokens

[bd]

In short, I have an app that I would like to tweet from a single account, but the authentication is failing. I have generated (and re-generated) the consumer and access keys. Using these keys in a OAuth.post(...) call, i.e.
function continuation(err, data, resp){ console.log(err, data, resp); } twitterer.post( "https://api.twitter.com/1.1/statuses/update.json", getContext().configuration.tasks.auto_tweet.apiPostKey, getContext().configuration.tasks.auto_tweet.apiPostSecret, ({'status': message}), "application/json", continuation)' yields{ statusCode: 401,
data: '{"errors":[{"code":89,"message":"Invalid or expired token."}]}' } ...`

a more detailed description of the problem here: https://stackoverflow.com/questions/41232327/twitter-app-oauth-with-node-js