When did you know that crate/rotate was a necessary evil in your house? What was the deciding factor?
We had a semi-serious incident at our house last night, and I'm not sure where to go from here...
It sort of started two days ago - I was fishing some treats out of a container, both dogs were next to me (one on each side), and Faust tried to lunge across me, because Sepp was apparently *too close* to the treats.

I managed to grab Faust in mid-air and crated him for the rest of the night.
Last night both boys were sound asleep, about 6 feet away from me... and all I heard was a sudden ROAR, and Faust was on top of Sepp. He outweighs him by at least ten pounds, but Sepp is a scrappy little shyte, and he WILL defend himself.
Anyway... lost of snarking, growling, pretty much a blurry ball of fur - it was ON.
I started yelling, and of course that didn't do a damned thing. I flew-hobbled over to them, and grabbed one by the collar and the other by the scruff of the neck to physically seperate them. neither one tried to bite me, and after I checked them over (no wounds... thank dog!) I crated them both for the rest of the night.
I have NO idea what happened, and most of all WHY this happened. There was no warning, no growling... nothing. I can swear that they were both sleeping...
I haven't let them go out together for the past few days, because my yard is a solid sheet of ice, and there's no way I could get to them fast enough IF they decided to get into it.
This morning I let them potty (seperately)... and right now they act like nothing happened. Lots of play bows, some good-natured wrestling, play growling, sharing toys like they always have.
Obviously I'm keeping a very close eye on both of them.
I will/can do crate/rotate IF I have to... I also want to avoid stressing Sepp, of course... he is doing extremely well between his lymphoma dx and the MMM, and I want to keep him that way.
Neither one has ever displayed any real DA... not at the vet, not at my house, not on the street when they encounter other dogs.
Sepp will be three in June... Faust will be two in March.
So - where do I go from here? *scratches head*
I've always been prepared for the possibility of having to keep them seperated from each other, but so far I've never seen any real animosity/aggression - they always seemed to enjoy each others company and often one will seek out the other to initiate playing or wrestling.
I'm at a total loss right now.
Any input is greatly appreciated... their safety is my top priority, always.