Our pups, Belle & Baloo, are both 6 months old and can old their bladder for about 2 hours max. Your dog is just probably really smart and figures "well if i ring the bell now and it takes 5-15 minutes to get outside (depending on stairs or elevator, or maybe you just carry her) then I'll really have to go!"
But I'm glad to know our dogs aren't the only ones with a weak bladder
