FWIW.
This am after parking my car for 4ish hours on a incline (rear lower than front) my dash gauge showed one bar flashing. (i always check the guage before starting the car). I was quite surprised to see it that low, as I have never seen it that low before. Fortunately I still have the dipstick otherwise I would have been concerned.
It read fine on the guage before parking it and read fine on the guage when I got home. (the dipstick was fine at the start/parking/home.
Just that odd angle parking was enough to mess with the gauge. Personally, the dipstick is still king.