Len sat, expressionless

"Hi, Len. I've got something for you. Do you know what this is?" Our excitement mounted.

"Yeah, I think it's a guitar."

I opened the case, removed the precious instrument, and held it up to him.
​
"Yes, and it's yours," I said placing the guitar in his hands. Cameras flashed, applause broke out, the nurses cried, and Len sat expressionless, still unbelieving.

What do you think was going on with Len in this moment? He sat expressionless. Why?