I second Dick’s concern
“ also add a steel bracket over the seam on top of that post. Hopefully there is more than that joist to help the rafters from spreading. ” Strength is in triangles, but only as long as none of the sides change in length. I don’t believe I would trust the fasteners in that juvenile yellow pine which has knotty defects. I can’t tell how much overlap you have, but some sort of metal strap on top would be easy to add. You may not have much snow where you are, but wind gust would be another big concern. I spent years racing sailboats and have been out in lots of storms, and know that sometimes a strong gust can hit like dropping a cow from an airplane onto your roof.
Half the weight of all your framing, deck and shingles from half way out from the house is bearing down on your king post, which would be supported by the 4x4 chord, if there is any slip at that other joint. It doesn’t take much to flex a 4x4.
You can get Simpson metal fastener plates at any lumber yard, and I would get a long one and use lots of fasteners. That will be a simple and inexpensive improvement that should give you a little peace of mind.