I just caught my cat doing, what looked like, spraying. What should I do?

I have a cat that will turn five years old tomorrow. I just saw him in the Kitchen, spraying the cabinets. He's neutered, and hasn't had this problem before. Sure, he backs into things with his tail up, but has never tried to spray anything. [tail vibrating, is what it looks like to me] I don't know if urine is coming out or not. Is this something I should be concerned about? I've also noticed that occasionally, [not always] he will pee outside of the litter box.