Every now & then Nic will start yowling and running around the apartment like a maniac for no apparent reason. He'll stop, look at some phantom thing up in space, and continue, this usually lasts 10-15 minutes then he chills out. He's usually a quiet cat, but when he does this he is mighty loud!
If I'm sleeping it scares the heck out of me...Should I be concerned? The first time he did it I thought maybe he was hurt, but he seemed to be alright.