High idle @ cold start is intended. Car runs in open loop fuel mode (i.e. running rich) before reaching operating temperature, so pulls in more air momentarily.
You can always do the idle relearn strategy (what I do after loading a new custom tune or between cold and hot seasons). I personally use my SCT to reset my KAM memory but if you don't have one you can do the following to obtain optimal idle quality:
Disconnect battery > let sit for a while > reconnect >start car w/o AC on, let it idle until it reaches operating temp (watch the gauge on the dash) usually takes 5-10 min > let it idle for 1 minute at operating temp > turn on AC, let idle for 1 min > done, now do normal driving to relearn the rest.
2010 GT Premium - Automatic - Torch Red