First off...nothing bad happened.

I went to get Z'ev out of his crate and consternation. His bone is now in front of the crate instead of inside. Z'ev, however, is happy and wriggling all over to get out. Gingerly, I reach for the bone, keeping an eye on Z'ev...nothing, still wriggling in joy. Pick up the bone, still happy dog, now the hard part. Giving the bone back to him. Carefully, watchfully, reach for the carabiners, no problem. Now the door latches...no problem. But I only open it wide enough to hand him the bone. He takes it, gently, circles a couple of times, drops it and still wants out. I leash him and he wants to bring the bone, but I say no, tug on the leash and out he comes without much ado. Phew.

We go for a brief potty walk, return, he takes a long, long, long drink of water. Another phew - that boy needs fluids! Then, the games begin.

I put him back in the crate and shut the door, no problem. Problem is, he left the bone in the front of the crate, by the latches. I reach for the top latch and...

Here comes Cujo Teeth bared, mouth wide open, full on snarl We proceed to have a series of strong "No's" and "Down" commands. He at least, grudgingly responds to the down. Briefly. Then repeat for 3-4 more episodes. Then the snarling sort of morphs into aggressive husky trash talk. Which I returned in kind. And THEN he settles quietly Since he's quiet and relaxed, I finish latching the doors and leave. Go figure.

Amy,  I'm going to suggest that you broke pattern and it was unexpected,  normally you would latch the crate and walk away - maybe talking, maybe not,  But you didn't walk away, you reached for the crate again - and I'll bet that you didn't get his attention first and he reacted in surprise.  

Attention and communication are extremely important when dealing with a rescue.  It's a habit with me to talk to my dogs (even though we're long past "rescue" stage)  All my dogs like laying underfoot so when I turn around to get up I'm apt to step on a dog - at the moment, it's Sasha who's laying where my feet would come down, Sky's on the other side between me and the wall.  Before my feet hit the floor, it's "Sasha, look out" and she doesn't care,she makes me step over her, Avalanche and Sky both move.

I too talk to mine when they have something. Mine get very engrossed in what they are doing and could be looking right at you but don't actually "see" you, so I always talk. Andy they aren't aggressive with stuff at all. It's a little like walking behind a horse. you always put your hand on them before you walk around so they know you are back there and don't kick you out of fright. I don't know if I would give him bones just yet either. Would probably stick to bully sticks or something he could chew completely up until he is more settled into the situation and you.

Actually, the pattern was the same, Al. He went in the crate, I shut the door, then reach for carabiners to double latch the door.