You have a slight pressure leak somewhere. Normal..? No. As you have a 'leak' somewhere. Many people leave their pumps on all of the time and have no 'leakage'. Normal...? Yes.... as it is a closed system and pressure is bleeding off somewhere. It is not leaking back into the tank, as the pump is forcing the pressure forward into your piping system and not 'backward' into your fresh water tank. If you can not 'find' the 'bleed' and it is not visible then turn your pump off when not in use. I had a 'bleed' problem and it turned out to be inside the wall at the tube fixture connection. I am not saying that this is your 'problem', but you do have a 'problem. Water is 'leaking' (small leakage) somewhere. If it is under warranty, take it back and have the dealer find the 'leak'.
2013 Forest River Salem Hemisphere SBT312QBUD
2001 CrewCab F-250 7.3 PowerStroke Diesel
SuperChip, BTS transmission, 6.0 Trans Cooler