He Knows

I bought James a set of Godzilla figures on eBay but I didn't tell him about it. It came in the mail yesterday and I hid it in my room so when he got home he wouldn't see it until I was ready to give it to him. When I went to pick him up he got in the car and said, "I know you got me a Godzilla." He kept saying it. Usually, he asks if I will get him one or asks if I did. This time he knew. I didn't let on and I asked him about some other things on the way home. When we got to the house I went to the kitchen and he went down the hall. A minute later he comes out with the box, proud as can be.

How did he know that?