Is My Cat Senile, or Angry with Me?

I expect some smart alec answers. My cat is, neutered, 16 years old, and lives with two younger cats. He's always been a great cat. Last week, he urinated on my chest while I was sleeping in my bed. I yelled at him and he seemed remorseful.This morning, he did it again. He has a clean litterbox, plenty of food and water, and I show him lots of love and attention. What gives? Can he be getting senile?