Logically, I'd say it's more likely to have been a coinkdaink that you've given meaning, and as such, has reinforced his presence in your mind, consciously and sub-consciously, causing you to dream about him. There is no evidence that the human brain can see into the future. It's very probable that your brain will now be dreaming up all sorts of scenarios revolving around him, if he has left a particular mark on you; this is just what the brain does; it tests out different scenarios, explores areas we'd never usually go to, and deals with things we perhaps cannot in our waking state. It was likely easier to give meaning to this, because he's probably reminded you of your ex, which you of course had a strong connection with - "I know I was only attracted to him, because of the resemblance."

When I stopped seeing dreams in some magical way, I actually began to appreciate them more and understand them; they stopped scaring me as much. I recommend doing some research, perhaps looking into what Freud found, because he had some brilliant thoughts on it; ones similar to my own, actually. xD