Just in time for holidays, Google has added a minor change in their notification bar feature of their Google plus product. Their bell mascot is wearing a red holiday outfit to celebrate the Christmas / Holiday season.
You may see this by going to Google Plus, clicking on the top right bell icon and archiving all of your notification items. Google will then say that you have “All caught up!” to your notification feeds.
This is yet another creative use of their fun occasional Google doodles.