Yeah, that’s kinda normal. When I bring my cats home from the vets, they get all hissy and fighty and stuff. I don’t know if it’s a “vet smell” or a lack of normal “them” smell, or if they bring home another cat smell that they picked up from the vet… Anyway, it goes away in a few days. Maybe because they’re already kinda cranky from the fixing, it takes longer. If you have some of that cat pheromone stuff (Feliway), that might help. I think you can also rub a bit of vanilla extract on them, and it’s supposed to be this really strong scent that makes them smell all the same.