Postava was sent to AHL Grand Rapids on Thursday, Ansar Khan of MLive.com reports.
Postava spent the past week with the Red Wings on an emergency basis, and he went 1-0-0 with a 2.89 GAA and .889 save percentage across his two appearances with the NHL club. He'll head back to the minors since Daniil Tarasov (undisclosed) has been cleared to dress as the backup for Thursday's game against Chicago.