http://www.ccel.org/ccel/mcgarvey/gospels.passage.vii.html
12 Jesus saith unto them, Come and 757break your fast. And none of the disciples durst inquire of him, Who art thou? knowing that it was the Lord.
Who art thou?
None of the disciples dared to ask this man, who are you? Because they knew that it was the Lord.
If it was the Lord, why would the question arise in their minds? They’ve seen him on at least two other occasions. What is different here? Or at any time?
My thought is that there was something physically different about Jesus, that his appearance was changed. I don’t know how, but something had changed. They knew in their hearts that he was Jesus, but he didn’t look like Jesus – maybe not exactly. Something caused them to question their eyes but not their hearts.