back-payback

Payback that is overdue.

The act of retaliating or taking revenge against someone in arrears for harmful acts committed against you so long ago that your intended victim doesn't even remember what it's for.

Housemate: "Strange, I had a flat tyre this morning, I had to change it before going to work."

You: "Have you pissed anyone off lately?"

Housemate: "Not lately. Although I did run over the neighbour's cat a few months ago."

You: "Sounds like they've finally dished out a bit of back-payback?"