Angie... this is normal on the Direct Injected engines.
This is what alot of us notice on our 3.6.
The oil turns dark pretty fast.
These Direct Injected engines- do beat up oil quite fast... especially if you do alot of in town driving...
Take note--the color of the oil does not mean the oil is no good... Because its black does not mean its useless. (up to a certain point).
Some of the DI engines- especially in cold weather areas- will show signs of fuel dilution (fuel in oil) which will degrade the oil life.
Its good that you plan on getting a Used oil analysis.
Most of us Outlook, Acadia, Enclave, Traverse owners (all share the same engine/platform)-- who have had UOA- now change oil at roughly 5000 miles.
This is a safe point to change (the 2011's and up Lambdas- the Oil life monitor reaches 0% at about 5000 miles) which is what most of us realized with the UOA (the early models were going to 10,000 miles- which we found was a little off the mark).
But I change at 5000 (on my traverse it shows 50% Oil life left). I use regular Valvoline oil- this normal oil has shown very nice results for my driving in Los Angeles (its cheap too- available at Walmart). Others use synthetic--- but I find that Valvoline does a nice job for the price- and miles (I would not put in an expensive Synthetic if im going to take out oil at 5000 miles-- to me thats a waste of money.).....
But- when I said that the color will go darker in more stop and go--- heres an example...
I drove from Los Angeles to FLorida- in about 45 hrs---2100 miles... this is what the oil looked like- 1st pic..
then I drove back Florida to LA... the oil now had 4200 miles- (2nd pic).. it still has that golden hue. So 4200 miles on about 4 days. Oil looks clean.
My oil is usually way darker in my everyday driving here in LA- by 1000 miles...
2100 mile oil
4200 miles oil