I think alot of things could play a part in the "why" for the sudden change of behavior.
1-recent move
2-cabin fever
3-lack of excersise
4-food issues
You may not want to hear it,but I think there is a slight food agression issue with either one or both of those sweet faced boys.There are diet issues with one or both correct?
Although none of the above is good reason to bite the hand that feeds you,but I would lean towards the impulsed momment you were scraping dishes,(food) and the intense desire to snap it up before it went to the bin. Although usually mild mannered,it was "the moment" and the desire to get a scrap of food. I'm not saying he is starved by any means,but I think he was testing you.And the hand pushing him away,obviously he did not like.
I don't know what I would have done.The only one here I would remotely have an issue with would be Earnhardt.I have had close calls with him before,and it usually is while I am playing,but he tends to at times get rough. But he knows better to bite me to the point of breaking skin.That's a deal breaker in my book.And that may seem harsh,but I don't put up with nonesense with him,nor would I with any dog. I dare say,that in that moment,he would have found his big @ss on the ground,if he were to bite me or anyone.And it would only happen once,that's it,no second chances.But that's me.And he is not a sheltie.
I don't know Barb.What did he do after the fact? How did he act? Did he know he did wrong,or did he proceed to come back for a second chance nibble of scraps? I think I would chalk it up to him testing you,and possibly a bit of boredom,I know its not acceptable behavior,but I don't think really he meant to bite & hurt you.I think he was geneuninely going after the food.
I do hope you are ok. I think I would teach him a boundry,when you are clearing dishes,he needs to be in the adjacent room,as an onlooker till he knows his P&Q'S
I'm curious to know..how many of us dog owners actually do teach thier pups,manners while eating? Do you or have you (I'm speaking to the forum as a whole) teach thier pups at a very early age,it's ok for you to sit,handle,play with thier food while they eat?
I know I can honestly say,I can sit next to each one of these dogs,while they are eating,I can take thier dishes,and move them,I can put my hands in thier bowls,and touch thier food without growls,grumbles,or any issue. I feel it is extremely important that each dog is taught this.As one never knows who or what may come in contact with your dog while eating. I have even had Bumper come along an try to get nibbles out of Earnhardt's dish,or the shelties,and no repercussions.