Yep - I've had exactly this experience. In the past I had skunkworks'd a program which became a primary diagnostic tools at the company. It was maintained in an ad-hoc manner and a number of people worked on it over time. A few years later, I was adding a feature and something just wasn't working the way I thought it should. Tracking it down to some lower level networking code, I saw something that was just obviously crazy. Feeling real anger over how some inexperienced engineer had violated
my codebase with their incompetence, I pulled up git blame to figure out who was about to get an earful.
And there it was: Me - from 7 years earlier.
I'd like to think this happens to most of us that are around more than a few years.