The learning center here on Hubpages explains everything about hubscores here: http://hubpages.com/learningcenter/hubscore-hubber... Since our hubscore is based of quality, traffic and activity, I would say there are a few reasons a new person might have a higher hubscore.
A new hubber could be more active in the forum, Q&A and in leaving other Hubbers feedback in the comments. Lets say the veteran hubber has equal quality to the newbie. A vet might not feel the need to be as active as a new person. So even if your hub gets more traffic, the new person might have the hubscore because of their activity.
I am new with a good hub score, and I try to stay VERY active. The first month I was mega active and I started to slack. Then my hubscore dropped. As soon as I got active in the forums, questions, comments, rating hubs and hub hopping my score went up.
Traffic also plays a factor. Sometimes a new person gets the Google honeymoon, where they are higher in the SERPs, and then drop down until they mature. Because they are higher, they might get more traffic than an old hub.. if the old hub got hit by Google Penguin or Panda, then the traffic difference might be surprising.