Hi
The results of the medical exam are normally sent to the Regional Medical Office for that region. Since there's none in the USA, I'm assuming medicals from the US go to Ottawa. So the DMP did it right. When the Buffalo office will want the results, they will request them from Ottawa (with the help of the IMM1017 form that you need to submit with your application) and they will be sent to them.
I guess in the case when the Buffalo office would request you to do the medical, the results would go directly to them. From what I understand, that is the case for other types of visa applications where the medical is requested only after the application has already been processed. That might be why the confusion.
No, your first statement was correct, no medical results are ever sent directly to the processing office, always go to the Regional Medical Centre responsible for that office.
PMM