Engine monitor display malfunction?

At a stoplight earlier today, my ICE was running though I thought it should have shut down. I checked the engine monitor display on the dash, and it didn't indicate that the ICE was on, even though it very obviously was. The same thing happened a bit later. My worries are: 1) there was clearly an error in what the dash display was showing, since the engine was on and it indicated that it wasn't, and 2) maybe the engine really should have shut down, but for some reason it didn't .

I was hoping that some of the more tech-savvy folks out there could let me know if this seems like a more serious issue, or just a little computer glitch that others have experienced. Thanks for any insight you can give....

 

Thanks for the comments--the display I'm talking about is the goofy one with the image of the car, the two engines, the wheels, and the energy flow arrows. Somehow I seem to recall looking at that fairly frequently when I first had the car, and it being accurate. I haven't paid any attention to it for a few years now, though, and as I said, the other day it was as far off as it could possibly be--engine running at idle, no "flow arrows" in the image, revved the engine, still no arrows, started driving with ICE going, no arrows, etc. It seemed to kick in and work properly for a bit, then when I arrived at my destination and stopped, the ICE was again at idle, and no flow arrows. I want some of that Lab Grade equipment!