Even though there is no indication at this time that any accounts have been accessed without permission, they have taken steps to ensure the security of all accounts.
"We invalidated all credentials within Facebook and Twitter," they noted. "Although users may see their Facebook and Twitter accounts connected to their Bitly account, it is not possible to publish to these accounts until users reconnect their Facebook and Twitter profiles."
They instruct users to reset their API key and OAuth token, and gave instructions on how to do it.
All users are advised to change their passwords.