I had the same problem not just a little rough idle. The car was fine at speed but when I stopped it would idle often very low and rough enough to shake the car and often rev a bit. At first I thought it was bad gas and called the dealership they said I could take it in or wait to see when I refilled if the problem went away. So I waited then the check engine light came on so took the car in and the problem was diagnosed as some type of vacuum hose had become clogged and it was fixed for free under warranty.

Also for reference when this first started happening I popped the hood and noticed oil near the filler cap and thought I might have a faulty filler cap but somehow the clogged hose was causing this issue and was remedied by the repair.

 

The part they replaced to fix your car problem is called Crank case pressure regulator valve.

 

Well i drove it yesterday and there was nothing out of the ordinary. I didn't refill the gas tank and changed nothing about my driving habits. The real test will be on Friday when I need to drive 330 miles. We'll see what happens.

 

Quite a coincidence. I had the CEL come on last night, dropped it at the dealer
today(along with my 25K mile service as well, which was due in about 400 miles).
They found a faulty "crankcase breather valve" and replaced it for free under
warranty.

But I didn't see any noticeable change in vibrations though...