chance are it was excitement due to the cat, but you mentioned she does not know how to tell you she has to got, here is what I did to take care of that
I have a system with Lola that works like a charm. First I decided I wanted to use the bell method, I did this for two reasons, 1. did not want to encourage barking, and 2. our house is mulit level and my office is upstairs so I could not see her standing by the door.
I also take her out with a leash. When she was young we went out about every two hours. I always use the same door, I started by ringing the bells myself before we would head out and kept saying, Lola goes potty, over and over and would give her a treat immediately after going, (so carry some small training ones with you when you go out) When back inside I would ring the bell again. After a few weeks, I started touching her paws to the bell saying the same thing, Lola go potty, Lola go potty. Eventually she rang it herself
I have had her for over two years and she still rings the bell when she needs to go out, I still take her by leash and she gets a treat when we come back inside.
I bought a bag of jingle bells at the craft store and a long ribbon. I threaded about 6 of them through an end of ribbon in a clump and tied it on the inside know of my front door, it hangs about nose level. I have a travel set and bring it with me if I am visiting family, once she sees it hung up she seems more comfortable since she now knows what door to go for potty. Dogs are creatures of habits, so you need to be consistent and use the same door every time. I also like using the leash, often when people let them out loose you can't see where they go or if they go. This is also helpful for when I am in a hurry, she goes out by leash and does her business pretty quickly. Good luck