UPDATE: Duane (the father of my future grandchild) called me and said that the hummingbird could have been stung by a bee/wasp, this makes sense! There's often bees at the feeder and if a bird gets stung it will die almost instantly. Good one Duane, thanks :)
Along with the death, there was a birth while I was gone. Dallas doesn't like sticking her hand under chickens so she will only collect the eggs she can see (big chicken herself). I reached my hand under a no namer Barred Rock and lo and behold there was a little black chick there. I had told Hubby the next chick to be born is going under Midnight, she's been sitting the longest, and chickens will switch nests over and over until you never know who's sitting on who's eggs. No namer didn't seem to mind and finally, after two months, Midnight has her own chick and can finally leave the nest.