This is new. Looks like github is still "working" when it's down.

  $ git push origin master
  Counting objects: 5, done.
  Delta compression using up to 8 threads.
  Compressing objects: 100% (5/5), done.
  Writing objects: 100% (5/5), 433 bytes | 0 bytes/s, done.
  Total 5 (delta 4), reused 0 (delta 0)
  remote: Unexpected system error after push was received.
  remote: These changes may not be reflected on github.com!
  remote: Your unique error code: 4fce1b2367b5304dd3761538b8fd0c23
  To git@github.com:myrepo/myrepo.git
     a62b7f1..e88431a  master -> master
  $ git push origin master
  Everything up-to-date

Note: Values are fake, but message is real.