15civic

Hi. I bought a CPO 2015 civic (automatic) with about 30K miles about 6months ago.
The dealer had two of them at the time. I didn't think much of it but I noticed one of the cars didn't rev up when I started the car - I would start it and then the car would immediately sit right at 1000rpm or so at Idle. The other one, which I bought revs up to about 1800-2k RPM and then it will sit at 1500RPM. Over about 1-2minutes after starting the car the RPMS will slowly drop to 1000RPM and it will stay there.

If I change gears before those first 1-2minutes the engine will rev up a bit in between gear changes to close to 2k RPM, but if I wait for the car to settle down to 1000RPM this wont happen.

My question is:
should I be concerned about this at all - is it something to have looked at? I've noticed a touch more vibration out of the car recently ...maybe just because it has gotten cold, but it got me wondering if there is something going on with it.