Is this normal - Engine Reving/noise upon startup

[LemonXB]

Please tell me if this is normal (ie, I just haven't noticed it before now). I live in the SF Bay area, so cold weather is not an issue.
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The past few days, when starting the car first thing in the morning, it reves up to 2.5 and slowly descends to 1 over about 7-9 seconds (it almost sounds like it's ill when doing this).

It does the same thing, but only for about 1-3 seconds when starting the car after it's only been off for < 3 hours.

The car drives fine otherwise.

Background info:
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-2008 XB
-800 miles
-Use Chevron 87 Gasoline, though I might have mixed the last tank with some Shell 87.
-I use Cruise Control. A lot. I'd say 80% of the time the car is on, it's cruising at various levels between 55-70.
-Had a small side-to-side accident at 80 miles that required some paint and replacement of sideviewmirror. No structural or mechanical problems found by body shop or insurance agent. Car seems to have run fine/normal from 0-800 miles.

[Invertalon]

Yes it is, when "cold" the car will idle faster to warm up the engine and get the oil flowing.

At least, that is what I think it is for? haha

[LemonXB]

Well, that sounds good. I guess. Is there any reason that it wouldn't happen for the first 800 miles?

[buickid]

Don't worry about it, most modern cars with computer controlled engines raise the idle when they're cold. Every modern car I've driven does the same thing. :]

[draxcaliber]

i like how your name is lemonxb, guess you were planning on lemon lawing it because of the enrichment cycle.

why it didn't happen over the first 800 miles, 1. you either didn't notice it, or 2, it is summer, so the engine was already warmed up, or maybe you've been parking in the shade lately.

[swartzautoman]

its normal man, dont stress it.