Checked in at gate with frozen delivery at 0530 for 0630 delivery. Gate sends you to receiving with gate pass. Got dock assignment, backed in with doors shut and tandems back. At 8am got a text saying we could leave when our light was green. Since our light was already green we slid our tandems forward again and left. Gave guard pass back and he checked inside trailer. We've been here around six times, this is the first time they've checked back of trailer. People seemed friendly enough.