I'd like to know about this too. I started finasteride about 6 weeks ago and have noticed a lump in my right chest under the nipple- the thing is, my right nipple has always been more swollen and puffy than the left, and doesn't seem to look appreciably different now. I think there's a possibility that it's always been there and I just never noticed because, well, I was never looking for it. Also, until quite recently I was pretty overweight, which would make it very hard for me to determine any gyno developing then. Plus, talking to my mother, she noted that members of her side of the family are greatly predisposed to develop benign cysts.
For the record, I have no pain, even if I press hard on it. I've noticed sensitivity over the past couple of days but that might be because I keep rubbing them like a paranoid pervert, haha.
For now, I'm stopping the finasteride for a week to see if anything changes, and am going today to go get some Diindolylmetyhane capsules to be on the safe side.