Tamed sitting wolves are teleporting to me

I was mining down in a cave and one of my tamed wolves that I had sitting teleported to me down in the cave.  I went back to my house and was smelting some iron, I made the dog that followed me sit.  Before long, another one of my tamed wolves that I had sitting outside my house teleported to me.  That kept going on and on until now I have 4 dogs in my house.   Not really sure what the trigger is to make them teleport to me.  Thinking this might be a bug?  Thx.