I don't think they will view it as a weakness unless your GPA is very low (ie-so low that it is inidicative of you not being able to succeed in med school)-but since your grad GPA is fine-it indicates that you learned how to work with your learning disability. They won't use it as an excuse to keep you out of medical school. I would feel comfortable talking about any LD I had with a DO admissions person (or in a DO school interview) and I would emphasize how I had dealt with it, and how determined I was to not let it stop me from realizing my dreams of becoming a doctor. Talk about your struggle and how you overcame, that is a good thing, something that will show your awesome character.
I don't know if I would mention it in an MD interview, to me it would depend on the person that was interviewing me. Sometimes they are generally interested in you, sometimes they are brusque. Something you have to keep in mind is that, although Medic170 is right and they can't discriminate, that doesn't mean that the interviewer is not going to think you won't be able to handle med school with your disability, and that might affect his judgement on whether to recommend you or not. Interviews are a very subjective process. You have to learn to guage the atmosphere and whether the person sitting in front of you will be impressed by your ordeal and how you handled it, or not (most people would be quite impressed if you play it right). Good luck