I have a 1500 gallon septic tank with two 30' laterals. The system
is 12 years old and I have it pumped about every 3 to 4 years.

Is it normal for the soil above the leach field to be slightly moist.
I'm not talking about squishy earth with lush green grass growing on
top, just soil that is a bit more moist than the soil that is not on
top of the laterals, not muddy at all. Is some upward movement of
moisture normal ?
Perhaps through evaporation? There is no odor associated with
this and the septic system seems to be working ok.

Thanks