It depends on many things, not all of which were in your original post. Such as: whether you have any other debt, whether you have college savings for your child(ren), how long you are going to stay in the house, how long you have to go on the mortage, your risk tolerance, your tax bracket, etc. If you like the house, plan on staying awhile, and have no other higher interest debt, why not go ahead and pay your mortgage off agressively? You would save a lot of interest by doing so. On the other hand, you have a good rate and you are relatively young, so if the conditions in the previous sentence do not all apply to you, then perhaps other goals should take precedence. It sounds like you are in a great spot financially - congratulations!
Try this link to see how much you could save. Of course this is all before taxes. If you are itemizing your deductions, it's not quite as attractive.
http://www.youngmoney.com/calculators/loan/mortgage_payoff