The only thing that we can think of, is that he is missing PeaPod. Since he left, Nugget just walks around the house meowing, meowing, meowing, and meowing, almost on a daily basis. It's been a little over a month and a half since PeaPod left. As you know, Nugget took on like a father role with him. Could he still be missing him after all this time?
Anyhoo, here are two pictures. He's lucky he's so adorable.