thermostat on/off frequently

[frankadank]

alright guys so i'm new to this whole hobby but trying to get into the swing of things. after having an enclosure set up for about a month and doing many test and different options to figure out what works best in my environment i think i finally figured my tank out and the temps. BUT my thermostat flicks on and off repeatedly quite frequently. my UTH & CHE are hooked up to it at about 98° right now so i can reach the desired temps. i have a temperature gun and the surface area isn't getting to hot. but i am wondering why? and is that a problem/ can be a problem if my thermostat keeps switching on/off. i'm talking like every 10/15 mins i hear it. the probe is placed under the tank taped to the corner of the UTH with foil tape. thanks!