Greetings, so I had this conversation with a person… we have an event together and must attend to it timely.
She asked me at what time I was able to come, and I replied that it's my grandma's birthday and this is also a very important event to me, and that I would try to be as timely as possible.
To that she replied "Aww, what a fortuitous coincidence…" which could imply she thinks I'm lying, but not necessarily.
How is this called? Is it sarcasm, or possibly just passive-aggression? Or, if it is passive-aggression, is there a more specific subset of it to which the expression belongs?