Last night I was playing and reached floor 8 or 9 (sorry, I forgot to check) for the second time, and I found that the map had been randomized but all of my notes on the ground and walls were still in the same X,Y locations.  No idea what could have caused this.

That means "something" broke the random seed chain. Hummmm. Thanks for reporting this.
I will change how the dungeon generation works to ensure using an static counter instead the current "chains" system. Hope this will solve those weird bugs.

This will be added next patch!