Haha, in a way perhaps. His learner/master line (and his “underestimate my power” line) kind of makes me think a part of Vader wants to believe he is better than Obi-Wan. Vader may have built up this moment in his head for a long time, expecting another intense duel, only to be totally shocked by how little Obi-Wan put up a fight. I think the strategic reason is more about using Obi-Wan to find other enemies of the Empire, but I think there could be a more personal, selfish reason in there too.