Qubby

I bought a 2012 gmc 1500 sierra 5.3l crew cab. Has 111.111 miles. Wondering if oil pressure should drop below 20 to 18 when stopped for over a minute after truck has warmed up. Cold idle at 40 when warm runs about 20-30. Running down the high at 75 it stays about 25-30, when I step on the gas it goes up to 40 to 50. Is this normal? I just replaced the oil pressure sensor and the screen behind it.