I just rewatched the episode, you right. He went into gas store and he showed the ticket for the car wash then the camera shows blood in the bumper. I though the remaining blood was after the carwash done.
I'm not sure if it was mentioned or somebody here noted it, when Asher came back from doing a car wash, there still was a remaining of blood in the rear bumper of the car, that could become relevant at some point.