I've got a new Civic 1.8 ES about a fortnight ago. One thing I noticed was that when idling or just above idle, the engine sometimes makes a 'purring' / 'growling' noise - (sounds a bit like a toothed rubber belt running tight). If there is no noise, there is sometimes a bit of a 'click' and the noise starts, or vice versa. I've never had a i-VTEC engine before, so I'm not sure if this is normal or not. Should I take it back to the dealer to check out?