My '08 46K Prodigy had its 45K service today, and when I started it up at collection, it rattled. Ignition off, restart, no rattle. It's been doing this lately, but only when cold, and not consistently. The service guy thought it might be from the "vvti cams". Cold start, less oil pressure, rattle. If so, should this be replaced as it has been with the OP?