Vacation Weekend

We are celebrating this weekend! That's all there is to say. Here's a cool idea for something someone should create, an Ambiance Monetizer. Someone asked me what headphones I was wearing and I gave them a link on amazon to them. They actually ordered it. What they didn't know what that person's link was one of my website affiliate links, so I actually made some money off the sale. Should that person know? Should I split the reward with them. Am I being unethical for not telling them that they were a pawn in my great experiment? So far, I see that the order has been placed, but it hasn't gone into my "estimated earnings" yet. Well off to that vacation!