Dreams of this type almost always reflect what your brain is processing while you're awake - anxieties, changes, uncertainties - rather than being actual omens. The fact that you felt relieved in the dream is interesting: it could mean that part of you, on an unconscious level, feels the need for a change or a break, even if rationally your work situation is stable. The anxiety when you wake up comes afterward, when your conscious mind takes back control and reinterprets the dream in a negative way. It's not a sign that it will actually happen, but rather your brain communicating that you should pay attention to how you're feeling about work right now.