I have one that does that sometimes. I have 3 in my wineador, and I'll sometimes see the temp suddenly change on one, and yes, I believe it is usually by 4 degrees. FWIW, It hasn't been doing that as much recently, perhaps I'm just not seeing it?

I haven't worried about it much because I'm running 3 Caliber IV hygrometers in my wineador and 1 in a tupperdor and outside the one with that temp fluctuation, they've been great.