I'd say you've got nothing to worry about.
In reality your CPU is probably running at 38-40°, but thats still perfectly fine. (Asus configures their mobo's to intentionally under-report CPU temps)
Mobo temps are just about useless, really. The problem is that you have no real idea where its measuring that temp at. On some boards, that diode is part of the NB, on others its situated somewhere on the board itself. Where exactly it is will have a huge effect on its readings. (on my NF7, its between the socket and the RAM, right where the warm air from the CPU washes over it)
I wouldn't worry about its readings at all.