Kitty Has Special Way of Alerting Owner She Wants Inside

My cat knocks on the door and says thank you when she enters. Her name is Koosje and she’s about 13 years old. She always does this, so I found it normal until the video went viral. If I don’t immediately open the door, she keeps knocking every 30 seconds. She’s very shy, but once you start to pet her, she won’t let you stop. Credit: Alec Broos (@alecbroos) via ViralHog