Haha, yeah this happens all the time to me, too. Although these signs can be extremely obvious, the logic center of our brain at night is shut down. So when we see these dream signs, they don't always register to us. Someone could fly, morph into an animal, and shoot fireballs at and we can still be oblivious, just going about our day like nothing happened.
The trick is to perform RCs habitually so eventually we will do one in a dream. Then it will be like, "Oh, hey... I must dreaming!" This is when our logic kicks in.
I haven't had too much luck yet...