That simple door frame repair in St. Paul ate my whole week

I took on a job in St. Paul last month, a small bungalow where the front bedroom door had dropped about half an inch. The frame was so out of square that the latch barely caught. I figured it was a half day fix, pull the casing, sister the jack studs, reset the jamb. Turned out the whole header had twisted from an old roof leak that was hidden behind the plaster. Once I opened it up, I had to cut out the damaged sill plate and shore up the floor joist underneath. Rebuilding that opening properly took me three full days, and I worked late on the last one. My original bid was way off, but I told the homeowner I would eat the extra hours because it was my mistake in judging the problem. Has anyone else run into a simple door or window repair that ballooned into a structural mess once you peeled back the trim?