radioactive kitchen tool

I bought a new mortar at Aldi yesterday. It's made from granite. So I dropped the γ-spectrometer into it over night. The radiation level in the mortar is ~50% higher as the background in my kitchen in the same location. The sources are the same (Th232 decay series and K40). I'm not worried. It was expected and the level is the same as above the tarmac on the road outside, which contains granite too. The radiation level in my house is very low. In a house in Saxony the radiation level inside of the mortar would likely be less as outside of it. Measuring radon levels in houses is a good idea, especially if you live in an area were those can be expected. Keep in mind the spectrum curve is logarithmically scaled! The device is a RC-103. Isn't it beautiful the measurement with a scintillator gives us a free FFT without the need to calculate it?