I've heard that it is fairly common for an engine to start consuming synthetic oil when they have not consumed regular oil in the past. I would suggest that you simply keep an eye on the fluid, as some people have told me that the consumption goes down or away after a period of time.
To truly find out what is going on, why not just pull some spark plugs and check for fouling? I have also heard that problems with your PCV could be causing the consumption also. Not to say that this is what is happening to you, they are mearly suggestions for things to try.
Good luck and keep me posted on what you find!