Inadvertent Sourdough

In an attempt to slow down fermentation and try the less-work-but-more-time approach, I made a simple sandwich loaf. I baked the bread after it fermented 3 full days (1 day preferment, 1.5 days full dough bulk rise, 1/2 day in the loaf pan) only working with it in the evenings after work except for quick folding in the morning and moving it to the loaf pan the last morning.

After baking it, I found it to have a slight sourness to it that I enjoyed (my wife, however, did not). I didn't set out to make a sourdough, but I guess I have.