Personally I would take it up with him before filling a complaint. Talk about it man to man, or maybe you already did. I know that is not cool what he did, I would have never done it unless I saw something that you didn't. Maybe a bird or another plane. Obviously you are pretty pi###d about it, did it constitue safety of flight as in where you close to the ground or all most stall and crash. If not I would leave the FAA out of this because you don't want to possibly ruin his aviaiton career. Obviously I don't know all of the facts, but from what you have said, that is what I would do. You can always use a threat of turning him in to the FAA.