Ghost in the Bathroom?

I don't get it. Every night, about the same time as when I start cooking dinner, Nicky invariably goes into the bathroom, which is right off the kitchen. He first jumps on the toilet (closed lid of course), then onto the counter. He'll start meow-ing and pacing back and forth across the sink. Some times he sits, facing the mirror and just cries.

At first, I thought he saw a ghost since he always sits on the same spot and cries! It was as though he saw something I couldn't see. Knowing this is probably ridiculous, I thought he might want attention or the faucet turned on so he could have a drink.

He seems worried, though, and doesn't want any water. Even if I do come to give him a pet, it doesn't help. Yes, I know I'm reinforcing his behavior, but what could this be making him so fidgety? I don't always go to him.