Check Ball Behind Oil Filter? Odd.

[StevieRaySTL]

So I'm changing the oil this morning (notice it's a little low) and hear something drop into the oil pan. Come to find out there is a check ball behind the oil filter and it popped out, so I tapped it back in, a little worse for the wear. It apparently regulates pressure to the oil sending unit. Now after doing some research (yes I searched) I find out that most vehicles don't have a part like this, and my mechanic is having trouble even finding a part # for it. ODD. Due to the fragile nature of the part I think I will need a new one so I thought I'd post here before calling Infiniti. Any one out there know of this part/problem or have any ideas? Thanx kindly for reading.