He hadn’t really wanted to take the bag (the environment and all that) but the cashier had given him a pointed look when he’d tried putting the carton of milk into his jacket pocket and with a sigh he had desisted.

It's probably for the best! He might've forgotten it was even there, or by the time he manages to dig it out of his dimensionally transcendental pockets, it would've already gone bad XD.

This is completely lovely. I love how you have them see each other again, at a point in their lives when they're two very different people, but still, with that connection between them. And what a fantastic twist at the end!