Looks pretty good from here. Not should why it would be stable. If you used nails you can sink a few srews in it to tighten it up. I can't realy tell from the picture, but anything that is going to be stressed by moving, bumping, christening it with your lady
, should have screws. Nails will back out over time.
Also, most trim in homes is made of poplar (one of the many known as whitewood) these days because, if it is sanded evenly it takes stain like oak and has a very similar grain and pattern for a whole lot less money.