Ghost-Busters Needed!

Maybe a case for my colleague Tube Dude who is fascinated by such things:

Last night on arrival in Barking sidings, I shut down my train to change to the west end as usual. As I walk through the train, I slam the inter-connecting doors behind me as I walk through.
Anyway, all inter-connecting doors are closed and I'm sitting just behind the west-end drivers cab reading a newspaper waiting for my departure time and I clearly hear the unmistakeable sound of inter-connecting doors slamming!

Now, those of you who know me (or read my comments on Tube Dude's blog about his ghost hunting) will know ghostly-type things completely freak me out! Here I am in Barking sidings alone on my train, which I've just walked through so I know is empty and I can hear the doors slamming!
I stick my head out the cab door to see if there's another train alongside me, which there isn't. There are a few C stock trains stabled over the other side of the sidings, but I wouldn't have heard their doors slamming.

I wasn't brave enough to have a stroll back down the train to check, I just locked myself in my cab!
It could have been anything I suppose, but the sound of the inter-connecting doors slamming is quite distinctive as I've heard it before when a fitter has been walking through my train. This time there was no-one. There may well be a logical explanation, and I've been desperately trying to think of one!

I'm dreading going back into Barking sidings again now! So Tube Dude, I suggest the next time you pass Barking sidings, see if you feel anything!