Growth/Comfort?

When this man heard that Jesus had arrived in Galilee from Judea, he went to him and begged him to come and heal his son, who was close to death. "Unless you people see miraculous signs and wonders," Jesus told him, "you will never believe."
The royal official said, "Sir, come down before my child dies." Jesus replied, "You may go. Your son will live." The man took Jesus at his word and departed.
John 4:47-50
There's something surprising about this story. The man asks Jesus to heal his son, and Jesus shuts him down! He says to the whole crowd that they're a bunch of non-believing people who just want a miracle. He wasn't only speaking to the man here, but the man was included in the crowd. But being persistent, the official asks again. This time Jesus heals, but he doesn't do what the man asks. He doesn't go back to Capernaum and heal the boy, he makes the man walk 15 miles home in faith that the boy is healed.
Why would Jesus have done this? Why didn't he go with the man and heal on the spot like he had done before? Why did he make the man walk back? What would the man have been thinking on the way back? The Bible says that he took Jesus at his word but he would have definitely had doubts during that trip home. What if? What if my son is dead? What if Jesus didn't really heal him? I have no visual assurance. I can't get back in contact with him. I didn't even get his address or his camel rego...
Jesus wasn't really concerned with the man's comfort and ease of mind, he was concerned with the man's growth. God is totally committed to our growth. If that means hard times, being stretched out of our comfort zones then he's quite willing to do that for the sake of our personal and spiritual growth.
No disipline seems pleasant at the time, but painful. Later on, however, it produces a harvest of righteousness and peace for those who have been trained by it.
Hebrews 12:11