sudden engine noise, I'm nervous

I started the 340 after sitting for a couple months to move it to the other side of the shop. when I started it it had a very pronounced ticking in the motor. I moved it from one side of the shop to the other and left it. It was cold and I was hoping that might be it. Today, I warmed the shop up and put an electric heater on the pan to get the motor a little warm. Started it up and it's still there. It wasn't there when I parked it last fall and it is a fresh rebuild.....any ideas?