Thanks, everyone for your replies!

I thought the same thing when I was told that he may be senile... he seems too young for that!

He has been in the same cage for years, with a tight hiding spot. Not sure what would set him off environmentally.

I feed him a large rat every 2 weeks, sometimes he goes a month between rats. I follow his body language and when he comes out searching for prey, I offer a rat. If I offer the rat before he shows signs of hunger, he tends to ignore it.