I think I'm going to have to agree with the idea of it being a conditioning thing. I've had numbness with my mountain bike and that is definitely a fit issue since I have to reach really far to the handlebars. But I don't reach on my new road bike. I will admit to lacking "core" strength or even any muscles there at all. In fact, it's a little big and needs to be toned a lot. I'm also starting to wonder if my hands are just weak and need to get used to the positioning of the handlebars.
Thanks for the advice. Again, very helpful.