So... I found in a piece of plastic in my food

Left this party late on Saturday but I didn't love the food so I was starving on my way home. Decided to stop at my fave convenience store for a late-night meal. Bought a pre-made sandwich, which I started chomping down in front of the TV as soon as I got home.

Guess what I found in my sandwich. A skinny piece of plastic, almost like a bristle off a brush.

OK, I can't even begin to figure how a bristle came close to my sandwich (maybe they brush the condiments on the sandwich?).... but it was one in the morning, I was hungry, and frankly too tired to A) stop eating and/or B) raise a classic Toni Ryan tantrum with an angry phone call or better yet, one of my famous sternly-worded letters.

So I ask you -- what is the correct mode of action in this kind of situation? I know your first answer will be, "Stop eating, immediately." But I was famished. And even if I was to raise a stink about it, what do I expect will come of it? An apology? A refund? Is it worth it?

Let me tell you, several years ago, the same thing happened to me at a food-chain-that-shall-remain-nameless that specializes in Mexican border food: There was a chunk of hard plastic in my tortilla. Wrote an email to the manager, which was met with a defensive blow-off, and an offer of coupons if I wanted to keep making a big deal out of it. #$%!& grrr. Needless to say, I've stopped eating there. (Well, at that location at least. I still love my chalupa now and again.)

So, as you can see, I didn't really feel like doing anything about it this time. What do you think?