Looks normal.

Tree looks nice and healthy to me.

Indoor branch dieback will occur with branches that do not get the minimal required amount of light also hot dry air from vents will desiccate branches.

These branches are generally at the bottom and don't get as much light (and I think I did some thinning up top when I brought the tree in to try to get the light to the bottom). Probably a week ago I turned the tree so this portion was facing the light (normally I rotate it a quarter turn each few days), so hopefully that will help.

I agree the tree on the whole looks healthy, but these branches are most definitely not. Attached another picture of the dying branches I pruned off just this morning. They look sickly as anything.

Looks normal and healthy to me too. Plants regularly shed lower/inner shaded leaves and branches in favor of outer and upper growth. A potted plant also limits the resources available and so you cannot expect the plant keep on putting out new leaves while still holding onto the old ones. Once a branch loses all its leaves like, the plant has no advantage to keep holding onto it and thus sacrifices the branch also. In nature, if you look around, happens with all trees/plants.

Not enough light to support all the inner growth or outer growth for that matter. That is why I cut mine back before bringing them inside for winter, plus what everyone else said)

Okay, sounds like the consensus is to relax a little (and get more light if I can). Good to know, and appreciate the help!

Twig die back could possibly be from lack of available light. However, most twig dieback is natures way of balancing the foliage and the roots.

I have dead branches on all of my citrus trees to. I don't like it but they seem to come back every summer when they go out side.

Yep, you're golden. It's not as aesthetically pleasing as we'd like, but it makes more sense from a plant's biology.

Congrats for keeping a tree as vibrant as it is.