temp switching between 90 and 95

[3.7 slp]

Hi all
this is a new one for me just fro my last trip I had the Cts replaced at the start of the year but when I'm getting is randomly the needle moves from the rock solid 90 up to
95 the odd thing is that when I let the car sit an Iidle it sits at
90 good as gold I have checked coolant and all is fine not smell just this odd move upto 95 and the back down to 90.
any tips ....thinking it could be cts playing up again.
Could do with this as have a house move to save up for.