It's not good to have it that full but I wouldn't freak out necessarily. There's no way it's a dipstick issue. I'd have them drain out the overage and note it on your ticket that it was overfilled by them - you need something in writing that they overfilled it. I doubt it did any damage but if something happens down the road you'll be able to pull it out and show it to them. Have them show you their handy-dandy digital, laser guided, solar powered oil dispenser. They'll probably feed you so much B.S. it won't be funny - be prepared for a battle. This is why I change my own oil, it's easy in the STi. My STi has never been back to the dealer - I hope to keep it that way.