Maybe it was just a one-time thing. Sometimes dreams simply aren't that stable, and that happens to me every once in a while: Some parts of my vision are blurred and dark, and sometimes the dream work vibrates in a sense.

Something that helps me tremendously, dream-control wise, is daydreaming about what I want to accomplish in my next lucid. I think about what it'll look like when I turn around and expect a door to be on the wall, and what will be on the other side when I walk through it. Make these daydreams as realistic as you can, and it will help.