Installed new water tank and well pump. Air in water tank is set at 2 psi lower than the cut in for the water pump which is 28 psi- water pump at 30 psi. Draw water 2 gal pump shut off and the psi in the water tank is at 56 psi shouldn't the water read 28 psi? Why 56?

No. You should have drained the system before setting the pressure above the bladder. Then, once the system turns back on, it's that same air that compresses as water is pumped in. The pressure at the top of the tank, therefore, will be the same as what you see on your pressure gauge.