The temperature gauge will rise up from it's mid point almost to the red and then drop back down to the mid point again. This normally happens when your at traffic lights or just parked up after a run. Also usually you have the Economy button switched on!
My car suffered from this from day one. I have had a new temp sender as well as a new iinstrument panel to no real effect.
I've spoken repeatedly to Audi Customer services and I'm told that it's designed to operate in this manor as it more accurately reflects whats happening in the engine and it's perfectly ok.
I wouldn't mind except that my dealer is still trying to fix it and so if it's deliberate then no one has told the mechanics.
If your unsure call Audi UK.