You have to get the opposite of what you think or expect if something is ironic. I don't think replying with "he" instead of "it" is something opposite of your expectation. It is rather surprising as if it were spoken by a mentally insane or retarded person. It is not a humor, either.  

Here are some examples of [irony](http://www.merriam-webster.com/dictionary/irony) in Merriam-Webster. 

“What a beautiful view,” he said, his voice dripping with irony **(atually, he is not looking at a beautiful scene)**, as he looked out the window at the alley.

 She described her vacation with heavy irony **(she is resting, not STUDYING)** as “an educational experience.”

 It was a tragic irony **(he got sick by his own worries)** that he made himself sick by worrying so much about his health.

Your case is just one of many [misunderstandings](http://www.merriam-webster.com/dictionary/misunderstanding) that can happen in your life.