My '09 consistently idles around 1500 rpm after starting the cold engine. It will stay at that speed for about 30 seconds and then have a stepped decline of about 100 rpm every 30 seconds before it settles around 750. Is this something to be concerned about? If so, what is my next move? Is this a simple DIY or something for the shop? Many thanks!

 

Sounds normal for your car.

Although, not related, have you brought your car in for the PCM/ECM software recall/updates? One of the software updates (TSB 11-049) is to update the software related to the fuel injector timing and VTC timing at cold start.