The bloody rag

What exactly was the point of that in season 1?

The dog grabbed the bloody rag Michael was cleaning the car with in episode 1, took it inside and hid it under the table in the house, and we're supposed to think "Well this is gonna come back to bite him in the ass at some point."

But he finally finds it 4 episodes in, the detective is even there when he does and goes "Is that blood?" and he just puts in his pocket and its never brought up again nor does the detective even ask about it again. Feels like something that was set up for some big moment and its just found and nothing comes of it.