Oof...and he's knitting in the round on three needles; he is tough! (IMO, it's easier on four needles; less tension at the bridges, less ladder effect, fewer holes to fill.)
MatthewG comes a little closer to my theory about why the trip back seems shorter. When we're traveling somewhere for the first time, we're very busy taking in large amounts of new information, sorting through it and cataloging. When we make the return trip along the same route, there is far less information to process and our senses relax. The return is less taxing, easier, and seems faster.
Almost.
Do they have 'puppy breath'?