A theory which seemed to be accurate moments later when Luke dodged Kylo Ren’s swings with perfect agility.
I certainly didn’t notice anything that hinted at the eventual reveal, being too overwhelmed by everything else that was happening.
Instead, we learn that Luke’s real power comes from a mastery of the Force that allows him to cross galaxies.
Although to her credit, my wife did notice that Luke Skywalker didn’t leave footprints, though, at the time, she assumed the movie was implying that Luke was such a well-trained fighter that he was so light on his feet that he didn’t leave tracks.