Where's the problem ?
You are being overly sensitive, the gauges are such a design that they are VERY sensitive around the correct temp, just 5C will make a massive difference on gauge, nothing to worry about, don't forget the rads are also getting warmer air all the time going through them with better weather/warmer temps.
Most ford gauges are grossly inaccurate anyway I wouldn't worry if it were mine, so long as when in traffic fans come on and go off showing they've cooled the water suffeciently all is well.
tabetha