BamaVol, this is not a lot to go on. Was the potato salad sweet, salty, savoury, or what? Was it yellow, white? Did it have lots of additions in it or did it seem to be mostly potatoes?

I'm wondering if either of two ingredients played a role: bacon drippings and/or mustard?

We always made potato salad with a bit of mayo, a lot of mustard, chopped onions and chopped pickles (the standard Southern thing). But then the mustard and onions can be omitted, for sophisticates, and maybe sour cream substituted and chives?

Bacon drippings. Oh, gosh. That wonderful Southern secret ingredient.

Presumably you have had wilted lettuce, no? My friends from not-the-South have sometimes expressed concern upon hearing the term "wilted lettuce," but it is a glorious dish. Fry bacon, remove and crumble, add freshly washed (and fresh ) leaf lettuce to the skillet. (Edited to add: Also some thinly sliced green onion, optional but recommended, with green shoots as well.) Stir around until the lettuce has wilted. Add a mere dash of vinegar, some salt and pepper, and maybe some herbs.

So, since bacon drippings play a part in "wilted lettuce dish," might they have played a part in the mysterious potato salad?

We won't be able to help until you identify the taste just a bit more. Maybe a box of candy to your host/hostess? Maybe telling her/him that GOOD HOSPITALITY DEMANDS THAT THEY SHARE RECIPES?