You shouldn't get too upset over pronunciation of different words.
Take for instance the word, pecan. I hear a lot of people say pee-can. Yes it grates me but that is their way of saying it. To me, it is pa-con.
My town is actually known as the "Pecan Capital of Texas". At the courthouse, we have the worlds largest pecan, even though it is fake (being something like 9 feet in diameter and 5 feet long one might only assume it is fake).
What it boils down to is this; let it slide. You say something differently then others and they may be offended. If you don't let it go when others say the wrong thing, don't expect them to forgive you.
Of course I am sure you are only trying to rib MB over it which is totally cool to me. Jokes between friends are the best kind. While jokes at the others expense are even better.