I had the same issue. Intermittent, rough idling/vibrations when cold starting. Happened a couple of times over the course of 4-5 days, and would usually (not always) just go away if I stopped and turned off the car, then started it back up.
SA said I had misfiring (didn't see the exact codes) and they replaced the spark plugs and injectors. It's been running fine since then.
I'm wondering if occasionally using a fuel injector cleaner (e.g BG 44K or Chevron Techron) can help prevent this in the future, as injectors are not cheap. The funny thing is that I had actually run a can of BG 44K through about a month before I had my issue, but I bought my car as a CPO a few weeks prior with 45,000 miles so perhaps the damage had already been done.