Has anyone else noticed a regular click noise at idle every 15-20 seconds? I was in a drive through lane with my window open and the performance exhaust turned off (a combination of things that has never happened before) and I heard a regular metallic click noise (just one) every 15-20 seconds like clockwork for about 6 minutes straight. No other issues. Is this a "Hemi" thing? Any ideas if this is normal or not?