Oil Pressure Gauge

[Z Ya Later]

Ok, I've noticed since I first drove the car that the oil pressure gauge doesn't respond properly. Instead of the needle going to 0 when the car is off, it goes to 80. Then, when the car is cold, the needles hovers around the 65-70 mark. When its warm, the needle drops down to what seems like the normal spot (20-ish) and repsonds to acceleration and decceleration, but when cruising it stays pretty high (around 60). The previous owner had to have a head gasket replaced on the driver's side. Could this be what's causing it?