You might feel like you should just let it go and forget about it but seriously, you SHOULD write to their corporate office and complain. Like everyone else is saying, he was completely unprofessional and most definitely deserves some kind of action against him. He can think what he wants, but to say it out loud and in earshot of the customer - that is just terrible, and calls for discipline from his company!
And if nothing is done by the company, you can atleast feel better about the fact that you'll make him feel like a complete A$$ about saying what he said. He will feel so stupid and embarrassed, and he'll think twice next time before judging somebody he knows nothing about! You can save some future customers the same ordeal.
So sorry you had to go through that, after all the love and care you give your baby.
Grrrr what an idiot!!!!!!!