I agree w/Matt. I wouldn't say one thing about the gift sitting there. He's a grown man and this gift issue is between him and your parents. Guilting him won't make him feel any better. In fact, it may create more resentment from him towards you and yes, he would probably say this is another behavior from the past that he doesn't like. So, please, just leave it alone. You aren't his mother.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
