She is broody. Most likely the egg is no longer good, but, it really depends on how long it went uncovered and how long the egg had been brooded. I'd put the egg under her then wait and see. Most hens do not like being moved. If you have to move her it would be best to wait a couple day before doing so. With her present nest, make it so the whole nest can be moved. Put her nest in a low box where it is then when you do move her she will not have a whole new nest. It does help if a move is needed, but still no guarantees.I don't know, but she really seems broody. If you place her anywhere, she just plops down and stays there, and she's all spread out to keep the egg warm.
Unfortunately, it seems my hen is not that smart. We had to move her nest last night so that she doesn't get attacked by a predator, and this morning the egg was cold, and as soon as we opened the door, she ran to her old nest, leaving the egg in the new nest. Would the egg still be viable, it feels like it came from the fridge.