There was even a couple threads about it at the time (the re-skin was supposed to be temporary to celebrate 'Supergirl' not being on CW )
Yes this happened almost 2 weeks ago, the Friday before the show premiered. All the Supergirl NPC in the game were temporarily changed to the show's look and there is also a Legends version available. This was all done to promote the show to the DCUO players. My guess is with all the work they put into this, the "temporary" will last at least a month.