I think what was more implied here was sarcasm.
sarcasm
A tongue of which the user speaks of something the complete opposite of what the user means. It often has the best comedic value.
As sarcasm is usually meant for humour, was my comment meant to invoke humour, or was his comment meant to be humorous?
Irony
One of the most misused words in the entire English language.
There are several types of irony.
Socratic irony - When someone pretends to be naive about a certain subject, and uses his questions about it to point out a flaw in the established belief. This is often used on the TV show South Park, where the children often ask questions about a situation until the folly in a parent's decision becomes clear.
Sarcasm - Understatement, mocking overstatement, or heavy-handed irony (stating the flat opposite of the truth) where both parties are aware of the difference between what's said and what's actually happening.
Clearly, another misuse of the word irony.
Neither irony or sarcasm are best put across in text form, especially when neither party knows each other, and cannot define whether the comments are meant to be humorous or not.
I'm sure we have all had the meaning of some text, even to a friend misinterpreted, let alone a complete stranger.