Same uptick noticed here!
We too get couple of Exceptions for client accounts:
TwitterException: 401:Authentication credentials (https://dev.twitter.com/pages/auth) were missing or incorrect. Ensure that you have set valid consumer key/secret, access token/secret, and the system clock is in sync.
message - Could not authenticate you. code - 32
We’ve tried to generate new access tokens/secrets and also generate new app for this user but error remains.
I hope, this is a temporary effect 