Doc raises a good point. It's difficult to apply the requirement of repeatability to something like this to determine if it's real or not, but it is a good point nonetheless.
There are differences between stray thoughts and actual premonitions. With that training in my martial art group, half the battle is recognizing a "real" indication vs. an imagined one. In fact, it's best to try to recognize the difference betwen the two.
What I'm trying to say is that, due to our imaginations, it's easy to misinterpret a dream/feeling as being a premonition when it's really just a dream or feeling and nothing more. The difficulty lies in the (mis)interpretation of the feeling.