oil preasure issue , need help!!

Hey guys, just wondering if anybody could help me out here. I'm having a oil pressure issue on my 318. When I start the car its at like 50 psi then when the engine starts warming up the oil pressure keeps on dropping. When the car is at operating temp and idle the psi is at 10-15 . When I start driving it the psi goes up . does this mean that my oil pump is failing or????

Thanks