Who's afraid of the big bad wolf?

I set off this morning for a hack on Wolfie.  From the minute I got on, he was acting very spooky, shying at things in the hedges, open gates, things he generally sees every day.  I just put it down to the fact that he's had 2 days off in a row.  We headed down to the railway line and as we were about 20 yards from the wooden bridge he stopped suddenly.  Normally I have found that if I give him a couple of minutes to look at something, give him time to gather information about the object he is looking at and assimilate the information, he will walk on, normally without any further shying.  Not today though, his head was raised, every muscle tight, his neck was rock solid.  He has crossed this bridge a good few times now and although he's not fully confident at it, I found his reaction today strange.  I asked him to walk on and he started to back up.  Normally if he gets to this stage, the next thing he will do is half rear and spin.  I didn't want this to escalate to that today and undo all the confidence I have already installed in him in crossing the bridge.  Training is a fine line between creating new challenges and establishing a safe environment and I never want to demand so much from him to the extent that I discourage his generosity.  I didn't think he was just being silly, there seemed to be more to it than that.  Trying to keep my adrenaline low, I dismounted and walked him towards the bridge.  As I got closer I saw that on the other side a bike and cycling helmet were propped up against the side of the bridge.  I slowly led Wolfie across the bridge and as I did, I noticed that the owner of the bike was down the embankment at the river edge, almost under the bridge fishing.  I hadn't seen any of this from the other side of the bridge, but Wolfie had obviously seen or heard something.  I think if the man had came out and been visible, Wolfie would have been alright once he realised it was a person, but from the other side, it could have been a big horse eating alligator.  I got back on and we continued our hack.  I rode up into the forestry to explore a few tracks and see if we could find some new hacking routes where we can have a trot and canter .  We found a brilliant track which we walked along and then trotted and cantered back.  There were a few hills, low branches and fallen trees we had to negotitate.  Wolfie was brilliant and evidently loved it.  He really wanted to go and as I held him back he put in a few leaps and bucks, out of frustration I think, but the track was too twisty to go too fast.  We hacked home and Wolfie crossed the bridge boldly (the fisherman was gone).  We were out for just under 2 hours.  Wolfie was tired, but he marched home with his ears pricked.  I'd really like to be able to take him down and stand him in the river, but so far I haven't been able to find a place which would be safe enough for him to go sown, the bank is really steep.  I'm very impressed at how skilled he become at opening and closing the gate at the yard.  It's completely not horse friendly, but Wolfie has mastered every manouvere he is required to make to allow us to open and close it.  Clever boy.