I'm starting to think that, although Anakin and Padme should be the same age, Ben has to be older. He is about the age of a grandfather in ANH, not a father. If Padme, Anakin and Ben are the same age, then Padme would have been in her fifties when she had Luke.
In this case, I think Anakin and Padme have to be approximately thirty years old when Padme has Luke (and his sister), while Ben would be about fifty.
I imagine Ben meeting Anakin when they are about thirty and twenty respectively, thereby allowing time for a friendship to grow between them.
Any thoughts?