Yesterday I hopped in my car and went to the store. I didn't warm it up like I usually do, but then they say new cars don't need to be (except I find when it's really cold I can't shift).
I get up the street at normal speeds (25 or so) and I'm at a light waiting and I notice the car is shaking back and forth. Like side to side, not front to back. I put it in neutral: same thing. I hit the gas a little and inch up, it still does it. I even noticed it while I was driving for a little bit, but then it went away.
I have no idea what it is, but every time I go to Subaru they say there's nothing wrong with the car.