You have to consider two things as i have had the same 'issue' but with a GTX570
1. The card is driving nearly twice the pixel real estate and has to crunch more numbers and therefore produce more heat.
2. and someone might need to confirm but similar to what i discovered with the GTX570, apparently the card doesnt 'down-clock' itself into idle mode as a result of having two monitors or X amount of pixels hence the higher temps.
Seems a bit hot to me. I'm running 3 monitors off 2x SLI GTX 570s (overclocked to 875mhz) and they idle between 35-36c. Its really the load temperatures that matter but you might want to turn up your fan speeds a bit.