I recently got an e-mail from Github saying that I should review my SSH key:
Please review your keys and ensure you recognize them. If you have any doub
Try to push / pull to one of your own repositories on github. A message will appear that the current key is not authorized. In addition is the SSH fingerprint of the current computer and a link displayed where it is possible to review your keys. Follow the link and mark the SSH key from your computer as approved.