I've been watching a programme with the dogs (they actually watch TV intently, honest). The programme was about puppy day-care centres and the rise of them.
In this programme it said that (and I had to do a double take) that their viewing horizon is far bigger than ours, and get this, their sense of smell is 10,000 times more than ours (I knew it was much more but didn't know it was to that degree).
Frank would have picked up our scent and followed it home like yours. That period before you see them again pulls in road accidents, hiding in gardens, being shouted at by the wife. Scary 20 minutes till I got home.
He looked at me and I picked him up and hugged him. Told him he was a clever boy.
He walked over to the 'treat' cupboard, sat on the floor, looked at the door, then looked at me, and looked at the door again...