SF Allroad

I need opinions on why the coolant in my wife's allroad is in such sorry shape. I was shocked to find that the coolant on my wife's 2.7T allroad is in the shape that it is. I'm not sure if that is rust or what. The car has 94K miles on it and has been very solid, no leaks, burns only a quart of oil every 3000 miles, and is on its original coolant. I would imagine that if I added some radiator flush and changed the coolant that would correct the condition. But how did it get this way in the first place? Opinions, conjectures, etc?

<img src="http://www.gjlenterprise.com/audicoolant.jpg">

quickaudi:STFA

If no, do so immediately. And yes, a coolant flush would help, and 2 or 3 would probably be better.