Littlefinger did mention he imagines all possible scenarios in his head so nothing takes him by surprise. We already know Bran can't see the future since he predicted Arya would go to King's Landing. I think maybe it was a mistake for Bran to let Littlefinger know of his Greensight, it just allows Littlefinger to take that into account and adjust. It's like telling a terrorist where we will be watching. Watching won't stop a terrorist, he will just be more careful and use a different tactic.
Or maybe I like Littlefinger so much, I give him too much credit.
But I guess Littlefinger doesn't know Bran can worg into humans, so that might catch him by suprise.