I'm really no expert but here are my thoughts.... for whatever reason, maybe she was distracted outside, maybe she just didn't really have to go then but then she came in and decided wow, I really have to go NOW! We've all had that happen, right? Well, she came over to you and sent you a psychic message but you just aren't as good at reading minds as dogs are and you didn't get the message and she just couldn't hold it anymore. At least that's what I like to think happened. Someday, I hope to be a really good psychic but for now.....