Never. Stress dreams are like that. They always come back when you're feeling a similar stress.

(For military people, it's the "back in bootcamp" stress dream. That one combined with the "I have a final exam in one hour in a class I never knew I was enrolled in" makes a particularly effective combination of horror, overlaid with a touch of absurdity as you're trying to figure out how the heck you enrolled in a class while you were in bootcamp.)