Its probably coming time for a new rad, and a few other coolant system components(sensors, fan, t-stat). I found ours was leaking and loosing some of its cooling efficiency around 58k(changed it out). Head gasket issues are somewhat rare on these motors but anything is possible with Audi. If you let the car over heat more then once, you might be replacing headgaskets and installing remaned head. These engines do not like to be over heated at all. It also makes a difference if the car had regular coolant changes.