I have 12,987 mi on my 2011 wrx now. I had the same problem. It happened just last week. I worked a double and stopped at the dealer that morning on my way home. Told them about the noise, they made me an appointment for the next morning. I dropped off my car that night, just so it would be a cold start for them in the morning...... Next day, " Hello Mr.S, we couldn't hear the noise. Everything is in working condition. I am sure it may have happened, but at this time myself and the mechanic took your Subaru for a drive and heard nothing. Your car is ready though and we updated your ECU for the recall."
I was worried it was a throw out bearing, my car has a hard time getting into first gear when cold.(live on long island)