water pressure test result questons

I am installing a 16' section CI baseboard with a 90 degree turn on my first floor. It is in place and pipes go down to basement and ready to connect to the main line. I did water pressure test yesterday. I have purged all air out. The water pressure was 62psi and then I closed the water loop and separated it from water supply. I checked all joints and low points. No leakage was found. This morning the pressure is down to about 43psi. I checked all the connections and low points again. All are dry. I checked several times with my dry figures. I am wondering why the pressure goes down without air inside? Is this normal? Does this test pass or fail? Is this because there are still some air inside?