A few ° lower than my 5870, looks fine to me!
GPU's are designed to take quite a bit of heat.
With your low temps, it is not even breaking a sweat.
Unfortunately ATI is having their first spat of driver issues in quite some time.
With two displays your card is supposed to keep its idle clocks slightly raised for stability purposes (400/1200 on a 5870, yours might differ slightly).
When using Overdrive to over/underclock the GPU, the idle clocks default to their single display lows (157/300) and causes corruption on the second display.
Hopefully ATI will have this issue resolved with their next driver release....