I went down to some tunnels for some strip mining and when I entered a cave (it only happened in this cave, repeatedly) game messages indicated it could not locate signs, and gave coordinates. When I checked those signs, they were there, but blank. I re-entered them and went back to the cave and the same thing happened in the same spot.
Also, of note, I found Silverfish Monster Eggs in random stone blocks in the vicinity, despite being nowhere near a Stronghold (I dug through the walls in Creative. No Stronghold.)