This reminds me of a funny story with former/new employers.
I had a great relationship with my boss. He left for a new organization. A year later, his replacement called me into a meeting one day and said there was no longer a place for me in the organization, due to a reorganization and changes in the existing position. After some negotiation (I had a very good record), we came to a reasonable settlement and I was bound to confidentiality by that agreement.
Shortly thereafter, I sought and gained employment with - you guessed it - the organization my old boss had moved to. Ironically, the organization I left provided services under contract to my new employer, and it was my responsibility to evaluate those services and report not only to our board, but a higher regulatory authority. I was very specific about the shortcomings of the services offered, and as a courtesy we provided a copy to the organization before filing it officially.
The president of said company, never a fan of mine (I found out later the from the time my new boss started, she had been assigned the task of getting rid of me. It took her a year.), called my current boss and said in a voice mail that it was "inappropriate for someone who had been fired to be conducting the review." Since the terms of my leaving were confidential, and it was never stated that I was "fired", this was not a comment or thought that he should have been sharing. He got a call from my current employer to say that his outburst was not welcome, and a cease and desist letter from my lawyer that threatened action if he made any such comment about my employment record again. Apparently he took that seriously, because I never heard anything like it again and I didn't lighten up until they improved service ironically, after he had been fired.
I love good payback stories.