My male does that, he takes it, strangles it, lets go, and slowly "checks the mouse over" before feeding, it takes him about 20 minutes to check it out, and eat it. When he let it go, did you remove the mouse, or keep it in there?
Our female would constrict her f/t prey and then leave it without eating it many times a night. I started yanking the tail gently of the prey while she was constricting it to simulate it struggling/moving and we haven't had any problems with her not eating it since.