The beginning and the end?

[hoi polloi]

It wasn't my first job, but I started practice in New York in employment with a practice. That was 20 years ago. Since then I have owned and sold two practices and now, I am considering a part time postition right back where I began in that same old practice that was sort of my origin.
Is that unusual?
After 20 years I am considering going to work for the same practice and the same owner that got me started in the first place?
All the young professionals he has working for him are where I was 20 years ago.
Is that a good idea for me to go back?