Just did compression test...Help with oil pressure!

[2JZEFINI-17]

Ok I needed to replace my plug wires so I went ahead and did a compression test. The readings were 130 across all the cylinders. I put everything back together and installed the new plug wires. Now the car idles perfectly and never missfires(One plug wire was broken before so the car misfired sometimes). But now my oil pressure gauge(its an aftermarket one, installed by previous owner) reads 65 at idle, which unless its reading wrong is not good. while driving the car the oil pressure jumps to like 70-75. I think that maybe it thinks that 0 is 50 and so it really reads 15 at idle but I dont want to risk it. What could have caused this to happen?? All I did was test compression and install new plug wires. Please HELP guys.