gnomi | A Conundrum

I got home from the grocery store to find a jar of dried rosemary leaves in my bag that I did not purchase. It *is* hechshered (certified kosher) and it is the brand I buy. But I didn't pull it from the shelf, and it does not appear on my receipt.

Do I:

1. Return it to the store and explain that it was in my bag and I didn't pay for it (running the risk that they will think I shoplifted it and am now feeling remorse)?

2. Go back to the store and give them money for the jar of rosemary?

3. Keep and use the rosemary (I put it in tomato sauces and other tasty food)?

I like rosemary, and I use it, but I wasn't due to buy more for a while yet. Thus my conundrum.

Thoughts?

ETA: I called this morning, and they said I *could* come in and pay for it or return it, but it was fine with them if I just kept it.