I have been assigned the task of changing oil to all of the compressors in one particular rack. Yesterday while removing the oil screen and sleeve, I noticed some metallic fine debris in the screen. It seemed to be aluminum. I guess now that it comes from the wearing of the piston, rods or bushings. Nevertheless, the compressor runs smoothly with no strange sounds or vibration, stable pressures and amps. Is this wear debris normal for an eight year old compressor?