Shadow Cat

For probably about a year now I have been encountering a shadow cat in my home (learned that name tonight, it may not be the correct term). Most of the time it seems like a random trick of the eye or convenient shadow. Other times its just feels too real, also my mother has seen it once or twice. 

It's a medium cat sized dark apparition that is usually running around or walking by, I have never actually seen its features but it acts like a cat.

Most of the more meaningful times is when I will be walking down one of the hallways in my house, then this small shadow cat will zoom down the hall towards me and I have to catch myself so that I don't 'trip' or 'step' on it.

It even happened last night, I opened the door to my bedroom and when it was barely open the shadow cat ran out and I had to catch myself on the door frame so that I wouldn't step on it, I honestly thought that I had accidentally closed one of my cats in my bedroom.

I DO have two cats and a dog in my house - I am used to cats running around and getting in my way at times, but when there isn't a physical cat there...it's confusing.

I have had a lot of pets throughout my life and I've had many that didn't make it, but never in this house.

I'm wondering if it's bad to see such things and or if it means something significant.

If it is a spirit and we aren't going crazy I also want to know that I don't have to remove it from my home, it seems friendly aside from always almost tripping me.

Thank you for reading my silly experience!