I suggest you keep your bedroom door closed night and
day. Why take a chance? And at night I would keep both
Midnight & Tigger in the laundry room...does it have a door? It's possible the Lab roams around at night unless he's confined too, and a lot of dogs do love checking out litter boxes for "snacks". This kitty is in a crucial stage for correcting inappropriate peeing, and you need to be consistent and not give him any opportunities to slip up (enough litter boxes and cleaned out 2x/day). In my experience, generally speaking, male cats do have more problems with inappropriate elimination than female cats. That's why you have to be diligent and nip any unwanted peeing behaviour in the bud, and be consistent.
Hope your hubby is making up to Midnight by giving him extra loving and playing with him for his rough handling.