A bunker is built for the worst, so it is read as bracing yourself, withdrawing to feel safe, or carrying a fear larger than the moment needs. Coming out of one is seen as readiness to face things again.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.