A security check is read as being examined before you are allowed to move on. Dream books link it to feeling judged, to having nothing to hide, or to worry that something you carry will be found.
When this appeared in your dream, what were you feeling?
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.