When you respond to questions like that, it's like banging your head against the wall. Nothing gets accomplished. If there is a next time, try killing them with polite kindness. Something like, "I'm sure being rude and insensitive wasn't your intent; but thanks for your concern." And deliver it with a sincere smile if at all possible. Snideness kind of minimizes the impact. Once in a while, in this let it all hang out society of ours, people forget what manners are.