Probably stretching the imagination a bit here, but is it possible that for whatever reason he completely innocently traveled up north in advance of the home leg (who knows, to visit friends/family...any other reason in the world) stayed at a hotel and by pure coincidence, without previously realising, was the same place Boro train.
Once he's realised, he's sneakily gone to have a look and sent a couple of pics on WhatsApp along the lines of "Lol you're never going to guess who's training outside my hotel"?
And then needed a poo, hence the sudden trip to the toilet.