Mark,
Do you stop the lathe at all during the sanding process? It looks to me like there are some sanding rings in the finish. If you stop the lathe and sand along the blank (rather than around it), that will knock down those rings and give you an even smoother finish. To see what I'm referring to, look at your picture, then look at Fangar's Amboyna Burl pen and you'll see the faint lines in your finish. I happen to live close to several members, and that was one of the first things they helped teach me when I started, so it's something I'm particularly sensitive to!
Otherwise, it's a great looking pen!