When my car runs for an extended period of time it starts to get slightly hot, about 3cm over the middle...
If I let the car sit in one spot, it will rise a lil' more. about 3cm from the red. If I rev the engine, it will go down, if I drive it will go down.... It's really wierd.
Sometimes... it will go up really fast... stay there for 30 seconds then just FALL really fast and go back to normal... the water pump is brand new, and so is the thermostat, all OEM Honda.

Any clues?