I thought that it was sometimes said that rudeness doesn't have to be intentional to be rudeness. I am not seeing the OP as unreasonable at all, and I would have been offended by the waiter as well, even if I didn't thin.k he was making a jibe
Why? So many people here seem to think servers, in the capacity of their job, should just be automatons, never commenting on anything.
Waiters, cashiers, etc. are people too, and they are constrained for topics by the tacit requirement of something in common. What the two parties have in common is the service being rendered.
Why read anything into "Wow, you really liked that," beyond "Wow - most people don't care for asparagus that much; usually this dish goes back just picked at, if it's ordered at all"?