I just bought a Cervelo. The LBS matched the seat position, bar height, and all that stuff, to match my current bike. They told me to go out and ride it the way I like, then come back with a bunch of miles under my belt and they'd fine-tune the fit according to specific complaints I'd find. They also said the fit is good for a year, so that I can come back in after a few months and say "I've been getting more used to X, and now ..."

I don't know that "re" fitting is all that common, but it should be. Some cyclists can do a lot of this themselves, and others can't. For me, there are a bunch of variables, and they all interact in ways that aren't always obvious to me. I've tried doing my own fit, but I just can't get them all right at the same time. It's easier to pay a good fitter; they'll do in an hour what takes me six months.