Although your silicon is not extremely high at 18, I'd still double check all my air filter fitting/seals. AFE is supposed to be a good filter...? And remember that "acceptable" levels are up to 30 ppm.
Also, the last VOA I saw of ASL has it starting with 4 ppm of Si, so you really only had a reading of 14 ppm Si.
IMO, copper by itself doesn't mean impending trouble. If you had high lead or tin as well, then you might be concerned about bearings and bushings. Replacing oil cooler lines often contribute to higher copper readings. Also remember that up to 50 ppm Cu is "acceptable".