User testing, novice outperforms experts

Happy new year to all! Recently we are working on the findability of content elements by running tree testing. At the results, we encountered that novice users are better at finding correct options comparing to regular users. Have you ever bump into something like this before? How can I delve deeper the effect of level of expertise? Now, we are also running face to face usability testings with the same system. What qualitative would you be looking at to be able to explain novice outperforming?