Is there any superstitions / omen about a stray cat looking at you through a window at night?

It happened after I heard 3 knocks on my wall one night, and I promise you the cat didn't make them. It was loud and high up on my wall. It sounded like the knocks came from inside. There was an equal small pause between each knock. I was so scared I woke up my husband. He checked things out and went back to bed. Still creeped out I then noticed something moving in my window. I looked closer and there was a black cat looking in my window. Funny thing is I have now window seal for it to set on. Of course I didn't think of that until the next day when I went outside and looked around. I heard the knocking 2 more times in about a month. That is also the month my father died. I know it sounds crazy but it really happened and I talked about it to people BEFORE my dad died. I had heard stories about my grandmother hearing 3 knocks before someone died and I remembered it and acturally told my husband about it right after the first set of 3 knocks.