What is it with Bill Clinton acting weird on the campaign trail this election cycle?
I think a small part of it is boredom. For the most part, it's pride. The man has seen half his legacy repudiated throughout this entire primary, much in part from his own wife. The kind of party that he helped build is going in an entirely different direction than he probably would have wanted. He has had to outright apologize for major decisions made during his presidency, and he has little he can personally boast about besides an economic boom which he had virtually no control over in the first place.
Old Bill probably deserves some sympathy here.
