I'm generally in agreement that someone with dietary restrictions - whether religious, medical or legal (i.e. meat doctored with clenbuterol ) - is responsible for knowing what's in their food. So skhill, I don't think you did anything wrong.

But I have to say that as someone who doesn't eat pork for purely ethical reasons - I'm perfectly well aware that any vegetable, salad, bean or beef dish is likely to be po'kified - it would never occur to me to ask about pie. I didn't even know you could buy lard in consumer quantities any more. I knew it's a theoretical possibility, but I've never known anyone who's made pie crust with lard - butter, crisco or vegetable oil is all I've seen in the last 35+ years.

If you're in a farm community and getting your lard right from the farmer like everyone else does ... then all bets are off.