• a state of affairs or an event that seems deliberately contrary to what one expects and is often amusing as a result

By that definition you COULD say her response to your ironic question was also ironic.

Also note the thesauraus includes mockery causticity and sarcasm as synonyms for irony while not always the case ironic statements are often made in a sarcastic or mocking manner, and that's how I think most single speeders would interpret "where's your derailer" no matter what the context.