This is like when you first turn the key in older cars. All the lamps light up so you know they are functioning properly. They then return to the current status. Which hopefully is off
I agree it's a throwback to the old days but it's kind of silly in this implementation. Cars used to do this so you could see if the individual warning bulb light had burned out. When it's just an icon showing up on the screen, I'm not sure what function it's supposed to serve -- unless it's actually testing each sensor for the warnings and lighting up the icon that the sensor is working (which I doubt).