Thermo is jumping around in degrees with no room change

[pickledpython]

Hey guys. I got my stimmy hatchie last week, along with click clack, heat tile and thermo (all brand new)
The thermo was preset for me to 35°. I got her home and noticed that night the top gauge would jump from like 30-37° quite frequently, with absolutely no change to general room temperature, was night time etc. I have set it now to 33° just in case it got too hot, it still will jump from 28-36° though.
Snake seems happy, handling well, smashed two pinkies tonight and is just laying next to her hide on the warm side.

I'm just stressing over this thermo because I know she needs it warm to digest her feed....is it normal for them to be so temperamental in temps??

 

[Bonustokin]

Never used these thermostats before. There can be a bit of change with the temp, however 7 degrees is a massive jump. Have you got another thermometer you can place on your warm spot to confirm the temp is jumping, or if the thermometer on the thermostat is dodgy?
Also have you got the thermostat probe inside the click/clack, or outside?