I would consider stress to be anything outside of a dog's normal behavior.
My guys eat and then play, sometimes they lay down, sometimes the drink water, I let them do whatever they want. If I were to try to restrict what they are doing by verbally directing behavior or crating, I would consider that stress.
Also stressful would be visitors, travelling or major changes in routine.
But you know what, I don't really even think about it much. I am aware of the symptoms and have a kit ready with a tube if someone were to bloat. I just personally don't think that micromanaging a dog's behavior is going to help at all.