I think something like that would be a decent intro of a recurring npc plus a shop feature.
Also with your current gameplay I think it would be hilarious for a random enemy to unwittingly steal something from the shop and then be hunted down by the shopkeeps.
This gave me a spelunky vibe too, as I've never played a mystery dungeon game (yet)
But yeah if you steal an item from a randomly generated shop, and don't pay when you leave the floor (or shop)
shopkeepers try to hunt you down, on the next floor they start to appear, like 1-3 per floor maybe
But if a monster is getting hunted, as a real time event, that would be kinda cool
the keepers would give a reward for the return of their goods
also real time events should be a thing, sounds pretty cool