Hi, I have Ford Fusion 2010 SEL 2.5L, with 99000 KM, the engine temperature used to be at the middle all the time, summer and winter, but recently the temperature indicator started to drop down from the middle to the lower than quarter, sometimes at the second line, then it goes up, and again drop down, so should I be worried? What I would do to fix it?

BTW, is it controlled by a thermostat as the old cars or by the computer?

Thanks for your help in advance,