I think more accurately the display turns yellow when lane keep assist actively engages to pull you back into the lane.
On a related note I got to experience what the car does when you try to change lanes when it thinks a car is next to you. Blinker on, the light on the side mirror is blinking rapidly but the car was back enough that I could fit. When you try to change lanes the car very aggressively tries to keep you in your lane. I had to apply a lot of force on the steering wheel to get over to the other lane. Pretty cool feature that I can see being useful when not fully paying attention or fail to see a car in your blind spot.
