Last Night's Adventure Time was something of a disappointment. They made a big deal of making Princess Bubblegum younger to be a better companion to Finn, and then they age her back up in just an episode. Granted, there was good reason. Now that she was a minor, a real creep had come over to take control of everything. He was very into discipline and soon had everyone in the dungeon. Young Princess Bubblegum and Finn try to prank him away but that just gets them into the dungeon too. Princess admits she has greatly enjoyed being young with Finn but she has to think of her subjects.
As I said a bit of a disappointment, but I did find it funny that Jake the dog literally phoned his role in this episode. He kept calling Finn asking how he was doing with the Princess. He'd have helped but he was too busy playing videogames. Ah, dogs.