I was driving back from the track Sunday and noticed I had normal oil pressure. I went about 5 miles and looked at my gauge and it was reading 20 lbs of pressure ( was cruising at 65mph). I went a little further and watched the oil pressure drop to about 17 pounds so I pulled over and shut off the motor. The motor wasn't knocking or making any noise so I was hoping for a bad sending unit or something but I called AAA and they towed me home. Then I pulled my oil filter and noticed there were chunks of metal in the check valve about the size of a BB . I took the oil pump cover off and pulled the gears out and the top of the gear that attaches to the cam sensor had chunks missing from each tooth on the gear. I drained the oil out through a white towel and there is no metal in my oil there. The gear did gouge the cover up at the top of my pump so I just ordered a new front cover with gears. What would've caused this and has anybody seen this before?