I've been back riding after a20 year "break" ... Been going at it since mid April. Early on I was getting numb in my right hand 5-7 miles into a ride. As time went on the hand got used to what I was asking of it. I did cheet up the bars a bit, but I'm moving them back down little by little. I was out for about 80 minutes today and got in 26 miles. The hand didn't bother me at all.
I know I won't be that fortunate on longer rides, but I really think the more you ride the better off this kind of thing becomes.