My Theory blazer, which I initally feared was a bit tight in the shoulders and upper arms, has also relaxed, and it is lined. It's a thinner leather, but I still think stretching should be considered.

okay, went back, tried on and bought the medium. I don't have time to post pics... have to get going on the pies, but I think we are all going to agree the fit is better. And, I was able to zip it over a thin sweater.

Well, yay! I am glad you went back and tried it. I just had a feeling...