I had the same experience as other posters. My shoulders hurt a bit right after I bought a new bike. My LBS spent a goodly amount of time with me on handlebar choices and also with the position or tilt in the handlebar.

I forget what all the possibilities are but I ended up with a handlebar that is apparently designed for smaller folks (I'm 5'2")...I think the angle of the bend in the handlebar is more extreme so that I don't have to hunch over as much to go down into an aero position.

It made a big difference for me and it was completely independent of the fit of the bike frame itself.

Good luck!

- traveller